Bits and Bytes — 10 June 2011


USB DACs – all mouth, no trousers

Digital audio.  It’s too computer-y.

I blame USB.

(How’s that for an opening salvo?)

Permit me to explain further.

Let us consider the digital audio newcomer. Let’s call him Bill. Bill has an extensive CD collection and a trusty CD player that has served him well for the past 10 years. He isn’t going to switch over to a new method of playing music immediately. Bill’s not gonna sell his CD player, buy an iMac and rip 2000 CDs overnight. The transition needs to happen slowly. Firstly, he’ll probably want to buy a DAC to augment his existing CD player, but all he hears is chatter about USB DACs. A new language dominates the conversation: adaptive, asynchronous……huh?

There ain’t no USB port on the back of his CD deck and – like me – Bill doesn’t necessarily want a computer in his hifi rig. He doesn’t want to fire up Highway 61 Revisited with the click of a mouse. It feels wrong to him – a sentiment to which many would empathise. If you want people to convert, you need to give them flexibility, hold their hand and take them with you – a way out is as important as a way in. Bill needs a DAC with S/PDIF inputs USB-only DACs need not apply.

Down the track, Bill might then consider an all-in-one lounge room device such as those made my Linn, Soolos, Olive et al. These products might have their own unique quirks and limitations but they fill a reasonable-sized market hole – they bring digital audio to the lounge room WITHOUT dragging Bill Gates or Steve Jobs along for the ride.

An alternative step for Bill might be moving from a CD player to a streaming device. It too keeps the computer-as-transport at bay. Sonos or Squeezebox lead the field in showing us that digital audio doesn’t have to mean computers (in the traditional sense of keyboard, mouse and screen) residing in the lounge room. In fact, at under AU$300, the Squeezebox Touch could be the biggest bargain in digital audio…of 2011, no question. The onboard DAC is far better than many sub-$500 standalone units. You get a touchscreen-controlled device that streams music from your existing computer (which can remain in your study, bedroom, garage) and/or the internet. Squeezebox server is configured to stream thousands of internet radio stations, which for many newcomers opens up a whole new galaxy of music. If the Squeezebox Touch dealt only in internet radio stations, it’d still be worth the entry fee.

From a digital audio point of view, two things stand out when using a Squeezebox Touch:

Firstly, you don’t need to understand ‘how computers work’ to use it. Much like Apple’s iPad, you’re getting the benefits of computer technology without feeling like you’re using a computer. The touch screen interface is so intuitive that many folk won’t know (or care) that they’re using a custom Linux build.

Secondly, your computer doesn’t have to reside in your hifi rack. It can sit upstairs in the study. Or in the garage. The computer’s proximity to the amplifier is irrelevant. It simply needs be connected to the network.

The question then presents itself: which DAC? The Touch has both coaxial and optical outputs, so – as per a CD player – a DAC with the corresponding inputs is all that’s required (which the our newcomer Bill already owns). More observant folk (read: pedants) will note the possibility of pushing audio ones and zeroes out of the USB port. True – but it only works (well) for adaptive-flavoured USB DACs. Asynchronous boxes have issues with signal lock and introduce sonic (digital) artefacts. Boo. Got Squeezebox? Got Sonos? Once again, you’ve no need to concern yourself with a USB-only DAC.

But still manufacturers sweat it. They add 16/44 (Redbook) USB inputs to their multiple-input DACs and then worry that the consumer will baulk at purchasing their product because of such a “limitation”; it’s really not the dirty secret manufacturers think it is. Anedio are currently in the throes of upgrading the USB input on their excellent D1 DAC so that it handles 24/96. Peachtree’s refresh of its flagship Nova – now iNova – has done the same. Why the fuss? USB connectivity should be seen as little more than a convenience. It’s a supporting act to a headline band. That headliner band (for now) is S/PDIF. All this before the dearth of hires music is even mentioned. I’ve said it before and I’ll say it again: a 24/96 or 24/192 version of the same recording does sound better than its Redbook equivalent but supply comes up way too short. Much like USB DACs themselves, Hi-res evangelists are the Joe Pesci of digital audiophile world – all mouth, no trousers. Redbook still rules the roost and will continue to do so for some years to come.

So what of USB-only DACs? Frankly – what about ‘em? Controversially for some, I nearly always advise people to steer clear. “Only buy a USB-only DAC if it offers a sound that’s not available from any other box,” is what I say. Eric Hider’s db Audio Labs springs to mind. His DACs’ sound is unique. There’s a beguiling liquidity to the the sound of the Tranquility SE that I’ve not heard in any of my favoured sub $2k decoding boxes: Lite DAC-83, Audio-gd Reference 7.1 and Anedio D1. Hider’s unit is the only USB-chained DAC that has caused me a moment’s repose……to re-consider the MacBook or MacMini as full-time digital transport. Hider has done what few others have done: nailed Redbook reproduction. Using a keyboard and mouse to control my music night not be ideal, but the Tranquility’s sound quality pros might outweigh the computer-in-lounge-room cons. Y’see: pragmatism matters.

A second high(er)-end candidate for USB DAC pragmatism might be Ayre’s QB-9.  I’ve not heard one, but like db Audio Labs, Ayre exclude all but USB because that’s what sound best (to them).  Adding S/PDIF focussed circuitry (probably) erodes sound quality.

Exceptions proveth the rule?  Nah, saying so would be trite.

At first glance, desktop audio consumers might baulk at the “NO USB DACs BEYOND THIS POINT” signage.  Desktop audio is where diminutive form factor overrides the need for ‘best’ sound quality. HRT make good-sounding, cute-looking products for office workers, students and bedroom listeners – people who listen whilst they use a computer to browse the internet, check email etc. HRT’s DACs are USB-only…but, seriously: how small is your desk? Buy a DAC with an array of rear-facing connectivity (so that you can enjoy it in your main rig)…and buy a bigger desk. Or tidy it. Find a way to keep the S/PDIF door wedged open.

Let us now consider the experienced digital audiophile.  Let’s call him Nigel. Nigel is serious about the way USB data is transferred from computer to DAC. He likely won’t care for the DAC’s USB port. Why not? The expanding array of USB converter products points directly to the answer. Nigel already owns a USB converter.

Want specifics? The Audiophilleo 2 is a black box that sits between computer and DAC. It (asynchronously) extracts digital audio via the USB port of the computer (using its own clock timing and NOT the computer’s). It then re-clocks and converts the USB input a S/PDIF signal (which is sent onto the DAC). Nerds note: a USB converter that runs a separate clock for each of the 44.1kHz and 48kHz sampling rate families and handles data asynchronously is generally preferred. The M2Tech Hiface is another such product.

Once S/PDIF has run its course, new product revisions will be no doubt be coupled to DACs via protocol up-and-comer: I2S (which separates data and clock information). Few DACs currently support I2S (Lite DAC-83 and North Star Designs are two) – but whatever the outbound protocol of the USB conversion device – here comes the kicker – a computer connected to a DAC via an M2Tech Hiface or Audiophilleo will most likely sound better than a computer directly connected to the same DAC’s USB port.

Until such conversion technology is built directly into DACs (and is invisible to the user), the market for USB transports will continue to flourish. In the land down under, Lenehan Audio have begun housing a John Kenny-modded Hiface inside their flagship PDX DAC. That’s some serious sounding gear right there. Moreover, John Kenny himself has recently announced details of his new DAC that has his battery-modded Hiface baked right into the design. This is where USB implementations are headed…

…and until this design practice goes global (mainstream), neither the digital audio newcomer nor the experienced digital audiophile have serious reason to give their DAC’s USB input more than a second look. Consumers should not worry about USB inputs remaining adaptive and restricted to 16/44…and neither should manufacturers! Even if you’re going the full nine yards – from CD player to lounge room computer – you’ll need S/PDIF inputs on your DAC. With a PC or Mac as your main transport, you’ll have little need for your DAC’s USB port because you’ll ultimately be looking at USB converters to juice the very best from your DAC.

For many, USB(-only) DACs are a one-way street. They offer a way into the world of digital audio, but once in, you’re on a narrow road headed toward a dead end…and you’re using a computer. And using a computer in the lounge room is akin to wearing ill-fitting trousers. They look like trousers, they walk like trousers…but they feel uncomfortable.

I’m not saying USB DACs are irrelevant.  I’m saying that they’re a niche (USB) within a niche (DACs) within a niche (digital audio).  Therefore, they have to work harder for consumer dollars.  My over-arching message here is two-fold and simple to summarise: Prioritise Redbook quality. All other things being equal – prioritise S/PDIF connectivity…until John Kenny and Eric Hider ignite that match of conversation.

John Darko runs Digital Audio Review.  He lives in Sydney, Australia.
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About Author

“Words are trains for moving past what really has no name”. Paddy McAloon of Prefab Sprout wrote that in 1983. John Darko likes words. Words about sound. Words about technology. Words about sound and technology. He strives for eloquence in communicating the sound of hifi equipment using the pixels on your screen. To this end, John Darko runs from his home in Sydney, Australia.

(37) Readers Comments

  1. I cannot fully agree. The problem comes with the server. If you really want to run a high-end streaming system, you will set up a NAS of some kind, and running a LAN in your own house is too much for many non-techie music lovers. I have tried Linux-NAS (QNAP) and Windows Home Server, but they all suck: With every version of the software, new problems occured. Just the album art was a nightmare.
    Now I have finally decided to put my whole music into iTunes on an iMac (switching from FLAC to ALAC), and have connected it directly to a USB-DAC which is attached to my Accuphase amp. I still need to get a better DAC (will probably go for the AQVOX), but the whole setup is a lot more convenient now. The iMac looks good even in the living room, and the remote control works fine with iTunes, and iPad/iPod/iPhone work as a control point. No more trouble with the NAS in the LAN, just a good one-wire connection from one machine (iMac) to the other machine (DAC).
    What you describe as a one-way-street – to me it was (after three years with my Linn DS) the escape from a nightmare.
    I enjoy listening to my music again.

    • Hey – I’m delighted that you’ve found a way with digital audio that works for you.

      A couple of points though: you don’t HAVE to use a NAS for a Squeezebox. You can have your music stored on a ‘normal’ PC.

      Secondly, because you started with a USB-only DAC, you now have to buy a completely new DAC if you want to upgrade, no?

  2. John,

    I think you should get out more! The one thing that USB DACS does is allow the user to listen to more music. I setup a well known reviewer over the weekend with some other companies dac on a Mac Mini. Took all of 17 minutes most of which was snaking cables to the preamplifier, because as you know these reviewers have a ton of stuff on their racks.

    Anyways… with the QB-9 receiving Product of the Year in 2009 it has been a whirl wind of craziness everywhere… but the sound concepts of a well engineered Asynchronous USB is what is really driving this.

    Ok what is sound engineering and here is the point. Not all USB is done correctly. USB in the Async world that require drivers and end up using bulk protocols will fall prey to low priority on the buss and suffer from sound. Async done right requires two audio oscillators with very low jitter and the correct way of snaking the I2S feed to the DAC. This is important and as we have found with tons of other audio can be done poorly and the customer is the one who ends up hating a technology that can be correctly implemented and better any transport or server available.

    The big thing with computer audio is SPEED. Early on we found out WAV/AIFF files sounded better than FLAC and ALAC files even though they are outputting the same data??? We may never know why but we found that with the optimization of the computer with SSD drives and tons of memory and a good OS (Apple OSX sounds best) will make all the difference and this is why Servers suffer. They come to you with basic Linux OS and low CPU capabilities and even if they are optimized they really cannot keep up with what a correctly implemented OSX system can deliver.

    Plus think of it this way… there are probably 2000 companies writing, developing etc… products that are add on’s to the Apple product line. How many engineers are working on Servers? how about other companies? Zero… this is why Computer Based Audio has really come to it’s own.

    A computer is so much better at reading disks and dishing out music as compared to a transport. Heck a transport cannot go back and re-read an error in a track. Rip some 80′s CD’s and play them against your transport. You will know what I am talking about.

    Dealers all over the world are thanking computer audio as keeping them afloat during these economic times. Customers call, email, post whatever that they now have a ton of music on their hard drive accessable from their phones and other devices.

    For me when I throw a party, I am constantly looking at my iPhone remote app wonder who or what title is currently playing. Heck I just let it shuffle from Allison Kruase to XTC… love it all!

    just a little more biased than most about how good USB can be.

    • USB-only DACs hold nothing special over S/PDIF enabled DACs in terms of access to music, ease of setup. A Squeezebox is as good (if not better) than a Mac when it comes to usability and accessibility.

      The overall user interface of a Mac has a long way to go if it is to approach that of the Squeezebox. Using a touch screen is inherently more intuitive – particularly to those with an aversion to computers – than a keyboard/mouse.

      I will concede that a MacMini is a superior sounding digital transport when compared to a Squeezebox. A MacMini is an EVEN BETTER digital audio transport with an Audiophilleo attached. However, the Audiophilleo can’t act as a go-between device with MacMini and USB-only DAC. The DAC requires S/PDIF input.

      I agree that two oscillators seems to be the way to go with proper async implementation. Very few interfaces have two clocks though. I believe the Audiophilleo and both Hiface do?! <—- until the technologies use by these guys are built directly into *affordable* (read: <$2k) USB DACs, why would I (or anyone else) buy a USB-only DAC?

      I think I need to hear a QB-9.

      • John,

        Come on SPDIF… get real… This was the worst idea Sony Philips ever came up with. Do you know how it even started? I do, I meet the engineer ounce. He was tasked to create a way to allow CD players to be tested closed box. Having the SPDIF signal a test disk and the two analog outputs the engineer was able to test everything they needed.

        Look with SPDIF comes jitter, sure there are a ton of people who think they can solve that problem but really it’s a moving clock and moving clock means jitter. USB ASYNC dacs done right do not have jitter.

        Why would I want to go back to a CD player? I have litterally thousands of titles at my finger tips. I have over 700 high res titles.

        Look at it this way John. EMI records calls 2 weeks ago they are going to release as downloads a ton of stuff and they want my help. Tell me how is your little CD player going to play that stuff?

        What it sounds like to me is that you really have no experience here to be writing this. I know John Keny and what’s he’s done. He has been hanging around forums for the last 2 years trying to come up with a product. But really it’s not a product it’s an upgrade to some other product and it’s still SPDIF.

        I like the iPad, I created IOS devices that plug into it. But really computer speed is also an issue and while the iPad 2 is better than the original it is still nothing to get close to a real computer. I have the touch and really come on even with all the hacks out there it is marginal at best.

        John it sounds like your tied to SPDIF… have fun, you really have not experienced enough to be writing about it.

        Steve N. come on stop advertising.


        • Pity little old me, stuck on this huge Anitpodean island, not able to get out very much. No wonder I don’t know nuffin’. (Come on, Gordon, I thought you’d be above such patronising shenanigans).

          I’m not pro-S/PDIF – see my original article, it acknowledges the inherent flaws of the protocol and that I2S prevalence is just around the corner. And I’m not anti-USB. At least, I have nothing against the *inherent* qualities of USB (or any other protocol). I know that USB can sound good – Eric Hider does a superb job with his Tranquility DACs.

          So what does bug me about USB? As I have said MANY times above: it’s USB’s LACK OF FLEXIBILITY. You cannot improve a USB-only DAC with an intermediary box. John Kenny might well be upgrading another product, but it works.

          Can someone take a QB-9 and improve its performance (with a plug-in device)? No. I’ve not heard A QB-9, but it is has a formidable reputation. And price. Even IF the QB-9 has a sound that’s the best in the world (TM), as you correctly imply, there are MANY, MANY USB DAC manufacturers making products that aren’t even close to its sonic prowess. Because some of these are USB-only boxes, JohnKenny-modded Hifaces or Audiophilleos don’t get a look in. There’s the beef.

          John Kenny’s modded Hiface AND the Audiophilleo are both products that bring tangible improvements to budget DACs. Many of us cave-dwelling Aussies own them and like them. S/PDIF might be an inherently flawed protocol, but it has FLEXIBILITY that USB doesn’t. <—- L@@K! There's my point, once again.

          • Dear John,

            I’m getting pretty confused here, I guess because what you are saying makes no sense to me.

            If I understand your argument correctly, you don’t like USB DACs because the only way to upgrade it is to replace it. Now I thought that was pretty much true of all DACs, but I’m just a designer so maybe I’m missing something.

            Then you made a post that maybe tied the pieces together. Apparently you prefer a type of DAC where you can improve the performance by putting an extra box between the transport and the DAC instead of replacing the DAC. I suppose this makes sense in a way, because one could upgrade the sound of the playback system for less money than having to replace the DAC.

            But on the other hand, it is the most laughably ridiculous statement I have ever read. The only box that I have ever heard of that improves the sound of a DAC by putting in line after the transport is a jitter removal device. But this is only helpful for systems with jitter caused by the interface — S/PDIF.

            If you use an asynchronous USB DAC there is zero jitter caused by the interface. So of course you can’t add a box to make it better.

            Am I missing something here, or are you REALLY advocating the purchase of crippled DACs so that they can be upgraded later, instead of just buying a proper DAC in the first place?

          • I would have added this to the end of Charles post but couldn’t figure out how to do it. I was recently told of an interesting comparison where a WFS DAC2 was fed via its SPDIF input from an Audiophilleo2. When compared to the async USB of that DAC it was no contest – the Audiophilleo2 was better. This leads me and the others at that comparison to believe Async is not the entire answer.

          • Bill Hobba wrote:

            “I was recently told of an interesting comparison where a WFS DAC2 was fed via its SPDIF input from an Audiophilleo2. When compared to the async USB of that DAC it was no contest – the Audiophilleo2 was better. This leads me and the others at that comparison to believe Async is not the entire answer.”

            You have to use a bit of logic here.

            Both the Wyred For Sound and the Audiophileo USB-to-S/PDIF adapter are asynchronous devices. So if your anonymous third-hand report is correct, then the only conclusion that one can draw is that the Audiophileo implementation is superior to the WFS implementation.

            Just because it is “asynchronous USB” doesn’t mean it is exactly the same, any more than saying every “hamburger” is exactly the same. Some hamburgers are better than others. Some USB implementations are better than others.

            The fact is that the Audiophileo costs 40% of the price of the entire WFS DAC. So it is no surprise that it might be implemented to a higher level. Remember, there’s no such thing as a free lunch…

    • Gordon is one of the best engineers out there today and he makes some awfully good sounding products. So Gordon, would you consider putting a counter story up on PSTracks and we’ll give you center stage to talk about the virtues of connected audio the way you see it? We’d welcome the opportunity to publish it.


      • I’d love to see this too. :)

      • Paul,

        I am a terrible writer…. In college I flunked English (Poetry) when I turned in my RF paper (which I got an A on) for the assignment we had. I told the her that this is my Poetry and she told me I was out. I determined at that time that maybe talking liberal arts courses were not my thing and instead took electives in Physics and Math. Why not take more differential equations or theoretical physics?

        How about I write it with some people who can form sentences?


        • Sure! We will take whatever we can get from you.

  3. I can not agrree that USB and DAC´s and Digital Music are still niches. This years Hi End in Munich has shown many new DAC´s and Streamers, I might say that most brands now have a DAC ore a Pre-Amp with a DAC integrated or a CD Player with an USB Input.
    It doesn´t matter wheather you want to stream ore listeb via PC/Mac. It will be the future an I believe that the HiRez Musik offers will increase dramatically.

    keep swinging

  4. I wish I could get out more, but these DACs keep me busy day and night. Gah.

    I hear ya when it comes to “ease of use” and “enjoying the music”. There’s little doubt that USB DACs are very easy to set up. I’m not arguing against any of those things.

    You’re definitely right about not all USB being done correctly. Which is exactly what makes them a dead-end: the user cannot improve on the baseline product. With a S/PDIF DAC, the user can make such improvements – the Audiophilleo is fantastic at this.

    I recently migrated my main rig to a 2010 MacMini and haven’t look backed. It looks terrible – seeing email programmes, a web brower, using a mouse and keyboard…ugh – but it sounds wonderful. And it sounds wonderful because I’m using an Audiophilleo1 and a John Kenny modded Hiface as intermediaries between computer and DACs.

    Gordon – by all accounts you have a winner in the QB-9. I’m not doubting it, despite not having heard one. However, many newcomers to digital audio can’t/won’t afford a product like that. They’ll be buying something far more pedestrian and if it’s USB only, they’re stuck with that sound.

  5. This article creates a phony straw man and then destroys it. Copying CDs to a hard drive and then playing through a USB DAC certainly is easily done p by virtually any experience using a computer, to claim it is somehow less satisfying to click on a moss than to load a CD into a CD player is laughable. I can understand the ritualistic appeal that some feel about spinning vinyl, but have never heard anyone wax poetically about spinning CDs. And if an audiophile is confused by the prospect of a USB DAC, how in the world are they ever going to figure out the Perfect Wave DAC + Bridge + NAS + iPad (+ PS Audio firmware updates, ready to download after purchasing that SD card writer that you didn’t know existed until you called PS Audio). PS Audio’s claim that the USB DAC is a dead end medium seems completely self-serving. Seems like Wavelength and Ayre USB DACs sell like hot cakes on the used market, while Perfect Wave DACs sit unsold like yesterday’s papers, most likely because the Bridge makes most USB DACs seem like “plug in and play” products in comparison.

    • Phony straw man, eh? Nope.

      To proclaim that the preference for a CD player click is “laughable” isn’t your call to make. Some people *do* feel this way.

      Ripping a CD might be a trivial task *for you*, but it might not be for others. USB-only DACs funnel users into computer transports. They’re just not as flexible as their S/PDIF counterparts:

      1) USB-only DACs can’t be hooked up to a CD player
      2) USB-only DACs can’t have their sound quality improved by an Audiophilleo, Hiface or similar

      This is why I refer to them as a one-way street.

      Some audiophiles just do not want a (full-blown) PC setup in their lounge room. They don’t want to use a keyboard and mouse to navigate and play music. You can laugh at or deny their reasoning, but those reasons remain. It might be about nostalgia for CD or it might be because some people just ‘hate computers’. I know many guys that do, but they love the Squeezebox Touch, with which they are using a computer without the FEELING of using a computer; probably because they’re using a touchscreen and not a keyboard/mouse.

      I’m a BIG exponent of digital audio, but I hate firing music with a mouse click – it feels clunky. It’s the same action I associate with ‘work’ (on a computer). Interfaces for computer software players have a LONG way to go before they’re *satisfying*.

      I’d much rather use my iPad – that’s elegant. Elegance is important. AFAIK Only Fidelia and iTunes – and Pure Music and Amarra, by extension – support iOS app interaction. BUT, iTunes doesn’t do FLAC, so that strikes it out for me. Which leaves Fidelia. Their iOS app is ok, but it’s far from what I have with my Squeezebox.

      I think all of this ‘interface’ stuff might be fuel for another article.

      I didn’t know PSAudio had claimed the USB DAC to be dead. Interesting. From a sound quality perspective and in my direct experience I *can* see why.

      This is the crux of my argument: John Kenny Hiface + DAC easily bests the USB input of the same DAC. And you cannot add a John Kenny Hiface (or Audiophilleo) without a S/PDIF (or I2S) input on your DAC.

      So, if you’re making a USB only DAC, it had better sound superb (hello db Labs Tranquility SE)…..otherwise, why bother?

  6. I agree. The Digital Source is THE MOST IMPORTANT aspect of a digital playback system, whether it is coming from Firewire, USB, Ethernet or a CD Transport. Recent reviews of iDAC and Musical Fidelity DAC from TAS demonstrate this. Put a high-quality digital source into most DAC’s and they all sound more like each other. Most significant sound quality differences in USB and Firewire DACs are due to the differences in the interface designs IME. Secondary things are Tubes versus discrete versus op-amps etc.. Just because a USB interface on a DAC is Async does not guarantee that the result will be good, even as good as a CD Transport. It is however possible to design an exceptional USB inteface.

    This is why I put so much money and effort into the oscillators, power supply and digital design of my own USB interface. BTW, my DAC does have both USB and S/PDIF coax inputs, so one can try other USB converter interfaces, a Squeezebox or CD transport etc., even my own USB converter. I encourage anyone to do such comparisons. I am confident that I will win these shootouts. USB can deliver SQ that beats the best Transports and WiFi devices, even rivalling vinyl.

    As for controlling the Computer Audio system, I also like the iPod Touch or iPad solution. I also like using a Mac Mini, which I have found to be relatively trouble-free. Improved versions such as the make a significant improvement BTW. I hope to own one soon.

    The playback software out there is generally not as reliable as the Mini itself, but a necessary add-on to get the best SQ from the Mac. I have listened to most of the players and prefer Amarra 1.2 (older version). Amarra also has the advantage of a really good volume control and EQ that is indispensable and transparent. This EQ is like adding a $5K box to your system to fix the bumps and suckouts, only better. You can order the new Amarra and then download the older versions including 1.2:

    The advantageous thing about separates for Computer Audio is that it gives one an upgrade path, for both hardware (USB interfaces, power systems and clocks) and software (players and rippers). Buy a “music server” in a box and you are trapped into their hardware, player and their ripper. You dont have any idea how good a job they did on these and the upgrade path for technology advances is usually limited or non-existent.

    Steve N.
    Empirical Audio

  7. John,

    Really, there appears to be a bunch of nonsense here. As Gordon has noted, SPDIF is a flawed interface which results in higher jitter and degraded sound. While USB-SPDIF interfaces done right can offer good sound, a dedicated USB DAC (given same level of implementation) is less compromised because it has no SPDIF connection, period. Yes, you need to try out an Ayre QB-9, or a Wavelength Crimson/Cosecant.
    As far as controlling goes, you need not control a computer via a mouse and keyboard: most computer audiophiles are controlling their systems via a remote app and an Ipad, hey guess what, a nice touchscreen interface showing full album art to browse your library and choose what to play-not clunky at all, actually quite elegant.

    • Looks like you’re agreeing with me here – I would love to be able to control Audivarna with an iOS app. But where is it? The Fidelia one is OK…..just but nothing on the level of the Squeezebox iOS apps. That’s my gripe.

      I would like to underline that I am not anti-USB or pro-S/PDIF when it comes to their INHERENT qualities and abilities. I know S/PDIF is a flawed protocol. What I am saying is that S/PDIF is more FLEXIBLE. It’s all about FLEXIBILITY: you can put a device (Audiophilleo, Hifaceetc ) between a computer source and your S/PDIF DAC to improve the sound quality of said DAC.

      This amelioration CANNOT be carried out with a USB-only DAC.

  8. S/PDIF certainly could be better if it had a companion clock. However, with the new chips available now, the performance of S/PDIF can be really good. I have both I2S and S/PDIF coax on my products and when comparing them, the difference is not significant. The designer just needs to do the right implementation. I have modded Transports and computer audio devices for 10 years and most of them have poor S/PDIF implementations. It is this that gives S/PDIF a bad name IMO. The interface can actually be very good.

    I’m not saying that a USB interface in a DAC should be anything other than I2S, but with external USB converters using S/PDIF, the difference can be negligible. Just read the last 2 TAS issues, MF DAC and iDAC reviews.

    Gordon – you mentioned above that the QB9 received product of the year. Don’t you get royalties from this USB interface? Seems like advertising to me. Gordon, come on, stop advertising. And please use punctuation so we can understand your text…..

    Steve N.
    Empirical Audio

  9. I’m not going to enter this discussion as it has already developed into a contentious, & unpleasant series of posts. I wish however to take exception to Gordon Rankin’s disparaging of me & what I do

    I know John Keny and what’s he’s done. He has been hanging around forums for the last 2 years trying to come up with a product. But really it’s not a product it’s an upgrade to some other product and it’s still SPDIF.

    You really do not need to stoop to such low level commentary in order to try to boost your credibility & that of your products. If you are really that insecure about them, then you should take up another line of work.

    I have not been hanging around forums for the last 2 years trying to come up with a product – I’m a DIYer that has been on many DIY audio forums posting information & learning for far longer than 2 years. Nothing to do with hanging around a forum trying to come up with a product. I detailed my journey to a better sounding product & showed exactly how I achieved it so anyone could do so for themselves – DIY, get it? This was tried by enough people who thought it sounded excellent. People started to email me asking for me to do the modifications for them.

    So you know nothing about me as can be plainly seen!

    Secondly, the modifications I make to the Hiface are not just limited to SPDIF output as if you understood what John D said, my modified Hiface is being incorporated as a front end into Mike Lenehens PDX DAC. Do you really think that the digital signals between USB & DAC chip would be transported via SPDIF inside the box?

    Again, you show a complete lack of any consideration for anybody or anything that isn’t your product, it really is not needed if your products sound up-to-par & represent value for what they offer. If, on the other hand you feel that they don’t then I advise you to consider a change of occupation.

    So please don’t make these false & slanderous statements again!

  10. Hi Charles

    You’re the chap that makes the Ayre DAC, right? So very pleasant to be surrounded by such exulted company – you AND Gordon. I’m sure your Ayre USB DAC is one the finest in the world and is quite possibly an endgame move for many consumers.

    Ignoring the fact that you both have a commercial agenda here, I’ll continue with the discussion on the proviso that personal jibes aren’t forthcoming.

    (I am sure you’re above such nonsense, Charles.)

    This really didn’t start as a piece all about me, but I can see why it’s gone that way – you’ll probably say that I’m “wrong” and then I’ll retort with “I’m entitled to my opinion”…the usual internet foxtrot. But, hey, I’m willing to learn and I’m happy to admit mistakes/errors etc.

    My article initially considered two possible consumers – I was trying to put myself in other peoples’ shoes. Bill and Nigel are based loosely on people I know.

    As per my last reply to Gordon, you will see that I wasn’t advocating that SPDIF was the inherently the better sounding protocol, but that’s its application just isn’t as flexible as USB. Application, not sound quality.

    For many digital audio fiends – especially newcomers – flexibility is important. Let’s assume you’re right and that USB just nudges ahead of USB in terms sound quality alone. Some folk might be prepared to take the performance “hit” of SPDIF just to maintain some flexibility of DAC deployment: i.e. pairing their DAC with a CD player or with a Squeezebox.

    Surely you don’t deny that SPDIF inputs on a DAC have far broader connectivity application than USB? Sonos, Squeezebox, CD player. This forms the crux of my beef with USB-restricted DACs. That USB DACs cannot be upgraded by a third party box is also part of my reasoning, yes.

    You might think such reasoning as the “most ridiculous thing you have ever heard”. Fair enough.

    However, I shall put aside my “flexibility” thoughts for one moment and try to focus on sound quality.

    I don’t think SPDIF is *that* far behind USB in terms of sound quality. In nearly all DACs that I’ve heard that feature both SPDIF and USB connectivity on the rear, neither of them sound markedly better than the other. There are exceptions – yes – but my general experience points to a similar sound from USB and SPDIF. And yes, this is at the lower (<$2000) end of the market.

    Yet, nearly ALL of these DACs have seen performance gains from injecting a J Kenny Hiface or Audiophilleo to the SPDIF input. This has led to the SPDIF sounding to superior to the stock USB.

    I'm sure USB can sound totally amazing. I've heard ONE single example – as mentioned many times above – Eric Hider's Tranquility SE. However, *amazing* USB isn't mainstream practice for many manufacturers as far as I can tell. I am sure Ayre is another exception which is why I singled it out for more "pragmatic" consideration in the original article.

    What I'm advocating is that consumers try to get the best from their existing DAC. With SPDIF connectivity they can upgrade their sound without buying a new DAC.

    You seem to be saying that with an asynchronous USB DAC, such intervention – even if it were possible – is not only unnecessary but also pointless because there is no interface-induced jitter with async USB.

    That leaves me with three questions:

    But surely interface-induced jitter isn’t the only enemy of the DAC? What do you think?

    Is jitter the only thing that is improved by the Audiophilleo and/or JohnKenny-modded Hiface?

    If someone were to take a “good” $1500 DAC (with SPDIF input) and hook an Audiophilleo to it, could such a combo approach the sound quality of the QB-9?

    • Well John I did hear a $1900 base level PDX with an I2S JK Hiface. To my ears it bested a Killer DAC. People responding to this thread may not know of this DAC but it has been compared to all sorts of stuff and nothing is able to best it. The closest was a DCS stack which was considered a tie – the Killer was more musical – the DCS more accurate. It easily blew away all comers at a DAC shootout I attended last August. I believe the level of performance properly implemented USB can deliver is so large its really a new paradigm.

    • John Darko wrote:

      “That leaves me with three questions:

      But surely interface-induced jitter isn’t the only enemy of the DAC? What do you think?”

      No, of course not. Every single thing that we can think of matters, and there are many more things we haven’t thought of that also matter. So of course for a DAC, the interface and its implementation matters, the digital filter matters, the DAC chip matters, the analog circuitry matters, the power supply matters, the master audio clocks matter, the quality of the parts matter, even the chassis and support feet matter

      Not everything makes the same degree of difference. Some things matter more than others. But that is the task of the designer — to figure out what matters more and what matters less and then be able to provide outstanding value for the consumer.

      “Is jitter the only thing that is improved by the Audiophilleo and/or JohnKenny-modded Hiface?”

      I don’t know much about the latter. The former is a way to add a USB input to a DAC that lacks one. The Audiophileo is executed quite well, so it is no suprise at all that if one has a low-cost DAC with a poorly implemented USB input that it will sound better with an external USB input that is implemented to a higher standard.

      But to then turn that into an argument against buying DACs with well implemented USB inputs seems more than a bit off the mark.

      “If someone were to take a “good” $1500 DAC (with SPDIF input) and hook an Audiophilleo to it, could such a combo approach the sound quality of the QB-9?”

      First of all you have to face the realities of today’s economy. People are inundated with low-cost electronics of varying degrees of quality, nearly all of it built in China. Maybe it works for Apple to build iPod Touches for $400 in China because they build them by the millions and they don’t care about the dozens of suicides at these prison camps. But you can ask Paul McGowan how well it worked for a small manufacturer of high-quality equipment.

      Returning back to your hypothetical “good” $1500 DAC, no, even if you add a $500 external USB input, it won’t sound as good as a QB-9. The only way to get it to sound as good as a QB-9 would be to copy the QB-9 completely. But if you did, it would cost at least as much as the QB-9. It’s not like we just mark it up to some arbitrary price point that we think the market will bear.

      We make what we think are the best choices that will give us the best sound at a certain level of implementation. Anybody can always throw money at a design and improve the sound with better parts. Or they can reduce the cost by using cheaper parts.

      And to address the longer question interspersed throughout your post, the reason we left an S/PDIF input off was to keep the price down. You see, S/PDIF is a broken interface. It automatically and inevitably degrades the sound quality by using because it adds jitter.

      By throwing money at the S/PDIF input, the performance can be improved, virtually without limit. So the choices were:

      a) Include a cheap S/PDIF input just to have one. Then people would say, “This Ayre doesn’t sound too good, does it?”

      b) Include a proper S/PDIF input and have reasonably sound quality (still not as good as the USB input!) and double the price of the DAC.

      c) Leave the S/PDIF input off altogether. This is what we chose.

      If you have a USB input, that takes care of your audio discs. So what do you need an S/PDIF input for?

      The most common excuse I hear is to connect a DVD player. Well, that is a whole can of worms, and connecting a video system to your audio system will degrade the sound of *both* systems unless you use special equipment to isolate the two. So it would be a mistake to connect a DVD player in the first place. You are much better off keeping the two systems entirely separate unless you are prepared to spend a lot of money.

      Is there any other digital equipment with a digital output that you need a DAC for?

      • “But to then turn that into an argument against buying DACs with well implemented USB inputs seems more than a bit off the mark.”

        If you re-read my original article Charles, you’ll see it’s not an argument against well-implemented USB at all. Most USB implementations are anything but (as I’m sure you know) – that’s my point. [You will note that I excepted the QB-9 in order to set it apart from the thrust of my USB criticisms. Ditto the db Audio Labs Tranquility].

  11. Oh no…..wait……I think I’m getting my period. Back in a few days.

  12. Interesting topic. First I want to say the very best DAC I have ever heard is a John Kenny Hiface equipped Level 2 PDX DAC. Not taking the JK equipped DAC’s into account the ordering of the top echelon DAC’s ( I have heard and owned others such as the WFS but they were not what I would call top echelon) I have heard is the Base Tranquility, Tranquility SE, Base PDX, Level 1 PDX, Level 2 PDX, Killer DAC. However with a JK inbuilt even a base PDX blows away any of those DAC’s – it makes that much difference. Mike Lenehan of ML1 fame, and the maker of the PDX, has told me it is the biggest advance he has ever come across in all his years in audio – it is that significant. He actually hates computers and would not use computer audio if it was not for the increase in sound quality.

    To get across just how significant this is a friend of mine is putting together a system from scratch very similar to my system. He heard my system including the JK PDX but didn’t like it – it sounded too tight. We have since discovered it was the unbroken in Duelund capacitors that was the culprit. Now they are breaking in they are sounding more liquid. Last time he heard it he listened to some Patsy Cline and told me it was so good he nearly cried. Since then my system has got even more hours on it and I was just listening to Patsy Cline myself. She was divine – simply divine. I have always liked Patsy Cline but preferred Leann Rimes. Well Leann Rimes sounded wonderful but Patsy Cline was in another class to my ears. This is the type of increase – literally perception changing stuff. My friend is coming over Monday and I would not be surprised if after hearing Patsy Cline he really goes overboard.

    That is not the only perception altering story I know. A person initially preferred a transport to the JK PDX. He started listening to a Dire Straight album he never really liked through a transport. He then switched to the JK equipped DAC, but noticed it was not as good when he switched back to the Transport. He was hooked. He spent the entire evening and well into the wee hours marveling at a recording he previously didn’t like.

  13. There were 2 USB DACs that earned “Best of Show” from TAS at 2010 RMAF: Tranquility in the GR Research room and Overdrive in the Empirical Audio/Salk/B-P-T room. I have customer feedback that the Less Loss is also excellent (although limited in sample-rates).

    I haven’t heard the PDX. Is it a NOS DAC? Based on an older D/A chip?

    Steve N.

    • Hi Steve

      The PDX is a PCM1704 DAC using the oversampling filter. It uses an SSRP valve output stage. Here is a review:

      It comes in three levels with the output capacitors being the main difference (although there are others) – check out:

      I have directly compared the base level to the Tranquility SE which I also own and so has John. There is not much in it – with maybe the PDX being just slightly better. That said my Tranquility went on the blink and Eric has kindly agreed to replace it but is stuck here in Customs right now and probably needs something to be sorted out to release it. Anyway the bottom line is Eric thinks this latest incarnation is significantly better so will need to wait for the results of that. But the Level 2 I have is well above the Tranquility – its very hard for any reasonably priced capacitors to compete with the very expensive, but very good, Duelund capacitors it uses. That’s with the PDX being fed with a streamer USB to I2S converter. That has recently been replaced with a JK Hiface which listening tests out our way showed simply blew away anything else – top of the line Wadia transports – all sorts of things were tried including an Auiophello2 (it was the closest) – it made that much difference. John has heard it and his comment was the Tranquility was caught with its pants down. Fed with that it bests any DAC I have ever heard.

      However guys out our way here in Aus are interested in trying other stuff and I have recently ordered an EDEL board top see how it fares. Funny you replied Steve because I was thinking of contacting you to see if I could get an off ramp and see how it goes.

  14. “But surely interface-induced jitter isn’t the only enemy of the DAC? What do you think?”

    Jitter is #1 followed by digital filtering and compression due to poorly designed analog stages and power delivery design.

    “”Is jitter the only thing that is improved by the Audiophilleo and/or JohnKenny-modded Hiface?”

    IMO Yes.

    “If someone were to take a “good” $1500 DAC (with SPDIF input) and hook an Audiophilleo to it, could such a combo approach the sound quality of the QB-9?”

    Sure, here’s one:

    Steve N.
    Empirical Audio

    • There are some really reduculous comments going on here.

      I have had a CD for years (last one coplan 823)but have recently moved to buying a nas. Now I need a DAC. Now I don’t care if I use my iphone click a computer button or stand on my head as long as it sounds good.I don’t have a need to push a big button to make music play nor do I think the next generation does either.
      I still have a record deck (clear aduio) but this is the way forward. I run a home recording studio and know the benefits of decent sound cards over built in ones. I would go for anything over the built in card even if it goes over spdif. Most only run at 48khz and then freewheels at that.

      Dont assume we are all stupid and want the closest thing to a CD. I dont. I want much more and it is available now and spdif is so old hat. How about we get rid of USB and connect to a dac using Gig ethernet?

  15. Not sure if this thread is exhausted. If not a couple of responses and mainly a request for clarification.
    No one seems to doubt the acclaim heaped on the AYRE QB 9. (To the folks from Ayre: Be proud of what you’ve accomplished. No need to slam others even if you feel their products are not as good.)
    If I had $2500 I’d buy one.
    If I could find one used from someone reputable I’d buy that. But…no luck.

    So I’d like to understand all this better.
    Are the Ayre folks saying that NO connection, other than USB as implemented by the QB 9 can produce jitter-free music?
    Are they arguing that ANY other connection is inherently significantly worse?

    I currently use an M2Tech Hi-Face as modified by Mapleshade Audio.
    But my DAC won’t play Hi Res files. Thus the need for a new DAC.
    Could someone who supports the SPIDF connection answer the AYRE folks as to whether it can or can’t compete with the QB9 (assuming a very high quality DAC — such as the Bel Canto 3.5 or other similar piece)?

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