Computer audio, I am not convinced yet ......

I am extremely interested in using the computer (Mac or PC) as a source for a digital playback. It seems to be the right direction for modern digital playback, a good alternative to the age old CDP, has endless potential and most convenient. So, I got an EMM DAC2 (retail $10000) with USB input and connected it to an Windows laptop via USB. My preamp, amp, speakers and cables are also of very good quality. Played some track on my system from the PC (used Audacity software, a very good and high quality software for sound processing). In 2 minutes I had to turn it off. It is just mediocre sound compared to playing the same track through a $1000 CDP(Sony SCD XA5400ES). It is almost like listening to an internet-radio through my PC speakers. I was wondering what happened to my first rate sound system ? Later I replaced the Windows PC with a Linux based MacMini, hoping that I will get the result I wanted. But it did not improve much. I did not like the outcome. My listening experience with the computer set up was 4 minutes(2 with PC and 2 with Mac) total. Since then I have gone back to using the same old CDP. I think I blame on the USB interface for this failure. The USB interface has not come up to the state of the art of a modern CD player. I did not try other interfaces purposely. No High-Res, only 16bit/44.1 audio files. I dont listen to SACD. Fire Wire to USB, USB to SPDI/F, Fire wire to HDMI, Firewire to SPDI/F, and almost an infinite combinations of patch up ideas are out there. But I dont like a patch up solution nor do I like to compromise the sound in favor of convenience.

I have heard many audiophile friends changed to computer based playback system many years ago for good and they are happy too. But I am not convinced yet. I am eagerly waiting for computer audio to catch up. I am sure it is in the making but it still has to go quiet a long distance.

Your thoughts are most welcome.
Try SACD on your Sony 5400 if you want HIgh Res audio.

The 5400 is up to date CD/SACD playback, and IMO beats every digital file (computer based) playback with 24/96K or higher files that I have listened to.

The USB port technology is the problem IMO. Pro digital High Res audio processing for the film industry does not use USB.
There is common misperception that if a DAC has jitter rejection circuitry and stand-alone clocks then its immune from the imperfections of the incoming digital signal. Its not correct, the principle “garbage in – garbage out” is applied to this situation equally well (or equally bad),

Regular computer parts create a soup of electro-magnetic and radio frequency interference. They contain a plethora of clocks and other ultra sensitive components that must operate in that soup. This environment, along with the quality stability and level of noise of the underlying power source, impacts the accuracy of each of those components. Audio playback happens via “real-time” communication between the server and the DAC. Unlike the data operations we use our computers for every day (downloading files, saving document and editing photos) audio playback has no error-correction built into the protocol. Consequently, most of the noise and all jitter created by the regular computer is passed along to your DAC where it may or may not be slightly attenuated by DAC circuitry.

Carefully select your music server (there are many choices today) and you will be surpised how mmuch better sound is when its played as a digital file from the quality server (file is copied or ripped from CD) as compared to exactly the same CD played using optical CD Transports.

Until you HEAR it - all words are useless, IMO

Don cc55: I bet you never ever ever ever ever compared dsd files played from quality music server versus the same music played from SACD read by optical SACD Transport.

For illustration purposes I have APL HiFi NWO-MasterJ - one of the best CD/SACD Player&DAC in the world (at least extremely expensive) and I demoe it to a number of my friends and visitors and enjoy the moment then their jaw meets the floor..:--)

All The Best In Your Search!

Simon Thacher
Musica Pristina
Just like with CD players, you have to be sure the components work together and give you the sound you like. Some things to try.

Have you tried the Digital input from the Sony to the EMM? That would tell you how you like the EMM DAC.

Try J River Music or foobar Windows players, using WASABI Event Style (async) or ASIO. Audcity is usually used for editing rather than playback. Do you know what playback mode Audacity used? If it went through the Windows audio stack using dirct audio that might be the problem.

Try a different USB to COAX adapter.

I replaced my Classe CDP-10 with a PC system when it sounded at least as good as the Classe. It took while to get the right competition, but it now sends better than the Classe and I would not go back.

I would not jump to a quick decision. Unfortunately, PC audio does take some tweeking, just like non PC audio.
I am no expert on the DAC2, butit looks like the USB on the DAC only does 44.1KB and 48KB and I am not sure it has a separate driver. That makes me wonder about the async USB implementation. It came out just as true async USB was being implemented. It would be nice to know more about the USB implementation or maybe try a newer USB interface that will go to at least 96 KHz, if you can.
I don't know

I think you need to give it more than 4 minutes.

I ventured into pc based transport on Friday night as a major skeptic, and by Sunday night, I am convinced and no turning back.

I had your initial thoughts too during my first playback of a ripped CD but I gave it more time and what sealed it for me was some comments from my wife.

It sounds like you have a really nice setup, much nicer than mine so you should be able to reep major benefits with some time and effort.

go for it!
Buying a really good DAC and connecting it via USB to most general purpose computers could be a very hit or miss proposition. Don't give up. Once optimized end to end, results should be top notch.
Someone above mentioned the noise aspect of most general purpose computers. That is a fact and must be addressed. Physical and electronic isolation between computer and hifi gear is important. Close proximity of computer to stereo can be like Superman and Kryptonite. Longer wires may help to keep some physical isolation. I like to use Wifi connections as well to eliminate a physical wire connection completely. Achieve both together and results should be pretty good. ALso all DACs sound different. A DAC can be very good but not to everyones taste in any particular setup, much like a phono cart.
Thanks for asking this question. yes I have tried the Digital input of the EMM DAC2 and the sound was fantastic. DAC2 is a great DA converter by itself when non-USB port is used. I have no knowledge of how the USB is implemented. This is exactly the point. The technology has not been matured enough. Everybody is trying something in all directions to find the right approach which has not been achieved satisfactorily. I am not blaming the DAC2 entirely for the failure. The computer is also involved in the whole picture.
In general, it seems USB connections seem to be much more hit or miss for really good sound than older more established and standardized interfaces designed specifically for computer audio, like TOSLINK and SPDIF. I have yet to get any clearly bad results with either o those. Have shied away from USB so far as a result and have not tried it to compare, though my mhdt Constantine DAC does has a USB input.
Spectron & Mapman, yes you are right that the mediocre circuits in a general purpose computer and the noise inside it are the big issues. If that is the case then we can not use a general purpose PC/MAC at all for this purpose. The computer must be designed by an audiophile company carefully removing non-audio parts and selecting exotic audio-parts which will cost $30,000 and up like some of the exotic CDP or DAC ? It may or may not run my 3D graphic software at its full speed. I will not call this specially designed audiophile grade computer a computer at all. It will be an alternate transport which happen to use some processor and useless outside audio application.
There is no rational set of arguments, facts or opinions that will convince you.
Most manufacturers are adding USB interfaces to their DACs now without much experience with these. As a result, most of these DACs sound better driven from S/PDIF input rather than USB input.

The other thing to realize is that even the very best USB interface when install in a DAC will likely share some part of the power system, ultimately compromising it.

The best course is to buy the very best outboard USB converter and then power it from the very best power supply. This will definitely beat even the best transports on the market. There are some companies that are shipping 5th generation of these interfaces.

The other thing to realize is that the player software and computer hardware is critical. I recommend Amarra on a 2009 Mac Mini powered by a Hynes power supply playing .wav files. Nothing touches this IME.

Steve N.
Empirical Audio
Don_c55, I don't have any SACD media. I am sure SACD will sound better than the Redbook CDs, but I have no plan in investing on SACD. Thanks for the suggestion.
Mapman wrote: "it seems USB connections seem to be much more hit or miss for really good sound than older more established and standardized interfaces designed specifically for computer audio, like TOSLINK and SPDIF. I have yet to get any clearly bad results with either of those."

Well I have. I used to mod both transports and DACs from other companies and I found lots of crappy designs. Much of the time I observed that one company would design a S/PDIF interface and the other would all copy it, even though it was a poor design. I don't believe I EVER measured one S/PDIF output circuit that was actually 75 ohms output impedance.

As for Toslink, the earlier transmitters where inherently bad, but the later 3.3V versions got better. They all add jitter. Its easy to screw these up too, like forget to put the decoupling cap close to the driver etc..

I've seen it all. None of these designers are crack digital designers with a lot of experience IMO.

Steve N.
Empirical Audio
Topmost wrote: "I have no knowledge of how the USB is implemented. This is exactly the point. The technology has not been matured enough."

You listen to one interface from one company and you come to this conclusion?

You should audition more USB interfaces, and particularly USB converters. There is a LOT better to be had.

Steve N.
Empirical Audio

I'm sure that there are lots of bad sounding older Toslink and SPDIF implementations out there. Some cheap less capable newer ones as well. I have only tried SPDIF and TOSLINK in recent years and from companies that have some focus on good sounding audio products. Not the best or most expensive, nor the cheapest mass market stuff. I have been pleasantly surprised with the results that I have heard can be achieved. Definitely better and more affordable as a whole than was typically the case years ago with many analog sources of the day. So there has been progress in my eyes. Of course, there is always a way to do things better. USB use for hifi digital (USB is a general purpose technology being used now for hifi audio its not designed specifically for that) is newer and not as mature, and hence probably more problematic I would think still. The question is always how much does it matter and for how much. I suspect USB will become more mature over time and add more value in future scenarios where higher resolution audio streams specifically are involved. But currently, in applications where TOSLink or SPDIF suffice, I suspect it is still more hit or miss. That will change over time though as things progress though I would bet.
Steve. N., Thanks for the suggestion. I believe the 5th generation USB converter you meant the OffRamp 5 USB converter ? I will have to try this one. Can you also mention some other high quality USB converter ? What is the best quality power supply to go with it ?
A USB converter and then the DAC ? This will add one more stage in the signal path and one more pair of ICs, and one more power supply, etc, etc, etc. This is getting too messy !!! Four to five extra components for just replacing a simple CD player !!! That is why I like a good DAC unit with USB input which has been implemented correctly to minimize number of components as well as expensive ICs.

Also a DAC with high quality USB input and a high quality volume control will be my preference !!! Is there any such thing in the market which will outperform my Sony SCD XA-5400 ES player ?

Why must it be USB? WHy not just use non USB digital input which you indicated sounds good? I can vouch that it generally does in my case as well using various combos in recent years.

Unless I'm missing something, I'm not sure USB even done well will necessarily sound better at present. It may be wiser to hold off on USB for now. IT will either get better, more reliable, and less expensive over time or else something else new will come along. I think USB will be around for quite sometime, but in that it is a general purpose technology and not designed specifically for audio, it may always be more hit or miss unless one rally knows what one is doing in choosing.
Mapman, good question, why must be USB ? When I tested the DAC2 with its digital input I tested with the Sony Player digital output. I am not sure if every PC/MAC comes with a TosLink or SPDI/F digital output or how it will sound compared to the digital output from the CD player. But every PC or MAC comes with abundance of USB ports and even it comes with USB3 faster data rate. That's why I was more inclined towards the USB ports. After testing with USB and not liking it, I almost gave up and did not think of using digital port from PC. Now that you have raised this question, I need to test it with the TOSLINK port from a PC. Unfortunately, I have already sold the DAC2 as it was not getting used. The main purpose of buying an expensive gear like DAC2 was to use it with a computer to get some decent result. I can buy the DAC again for the experiment and even perhaps something better than the DAC2 available today.
"Can you also mention some other high quality USB converter ? "

Diverter HR

"What is the best quality power supply to go with it ?"

Modified Hynes SR3-12

"A USB converter and then the DAC ?"

Yes, plus a good S/PDIF cable. You can get really good one for only $250.

"Also a DAC with high quality USB input and a high quality volume control will be my preference !!! Is there any such thing in the market which will outperform my Sony SCD XA-5400 ES player ?"

Easily, but the separate USB converter on its own power and DAC is still better.

Overdrive SE or Metrum Hex DACs should do the job on their own.

Steve N.
Empirical Audio
"good question, why must be USB ?"

If you want to not only beat, but exceed the performance of the very best CD transports/players, you will need to use USB, and not just any USB. You will also need to use a good computer platform and playback software. It is not rocket-science. Its just like buying a Vinyl or CD system. Separates will always sound better. A preamp and amps will beat an integrated. A transport and DAC will beat a CDP.

Look at the systems that get best of show at CES, RMAF and Newport. Most use USB.

Steve N.
Empirical Audio
Topmostaudio: I believe your comparison between regular computer and music server (where you should not be able to run your 3D graphics) is correct.

" It [music server] will be an alternate transport which happen to use some processor and useless outside audio application"

Here I am not sure I unerstand it. Most even household electronics carry some processor so by itself its presence means nothing to me. "Useless" outside audio applications??? ...Depend what they are and how well they do their assigned job.

Audioeng: Indeed, most DAC manufacturers add cost effective USB interfaces which are not always the best! Stand-alone USB inteface make sense for me ONLY if it outputs I2S (not SPDIF !!!) but even fewer I2S inputs vast majority of DAC's have.

I would add only that very high quality stand-alone interface cost a lot. It could be much cheaper if USB output from a music server will be well designed and well executed, if music server designer would asume that USB DAC input is mediocre and do THE RIGHT JOB on the side of music servers. Not super easy but...possible

Of course, not all music servers and not all stand-alone USB interfaces are made equal...this why we do have EARS
Simon, I was referring to a computer of some sort with a CPU as in a normal computer, but the computer is designed for audio and thus will be extremely costly yet not usable as a normal computer.

I can see very clearly that with the on set of this so called computer audio, a new type of device called "interface converter" is going to find its importance in the audio system much like a preamp found its position in interconnecting various sources to an audio system previously.

So, the audio chain with a computer will look like the following:
Computer => Interface Converter => DAC => Preamp => Amp => Speaker.
Previously it was
CDP/TT => Preamp => Amp => Speaker. OR
Transport => DAC => Preamp => Amp => Speaker

This new component "Interface Converter" will convert various digital Interfaces (I2S/HDMI/USB/FireWire/SPDIF/TOSLINK) => Analog or
one form of digital => another form of digital signal.

The quality of this conversion will dictate the quality of the system sound. Better the conversion quality better is the isolation between a mediocre computer HW and a high end audio system.
I really like the "internet radio through my PC speaker sound” that I'm obtaining from my CAT amps and Soundlab M1PX speakers.

Gesh, generalization about interfaces and suppositions about a technology not yet being mature enough, are just that suppositions and generalizations. In my PC audio experience (as well as audio experiences in general), I've found that these 2-words define conclusions that always prevent one from making really wonderful discoveries.

Based on my satisfaction with the present status of computer audio, perhaps I fell into PC Audio trough that contained the only good hardware, but that’s simply not the case!

PC audio and the USB interface are as mature as any other high-end audio playback chain – e.g., box vs open baffle speakers, planars, horns, active/passive preamps, no preamps, vinyl, M/M vs M/C cartridges etc….. Will advancements be made in each of these audio niches, you betcha. Should one put off buying one of these niches, because they’re not yet mature enough, no.

Years ago I moved from a Wadia 861 CDP to computer audio and haven't missed a thing sonically. My first USB DAC was a Wavelength Brick Silver. My present DAC is a Wavelength Crimson.

In my system, high definition files (96/24 and above) sound extremely close to vinyl which is being spun on a Galibier turntable, Tri-planar tonearm and a Dynavector XV1s cart. So, from that standpoint, my audio buddy's systems and from many of the rooms at 2012's RMAF, great digital audio (and yes, USB derived) can be had with a little effort and not as much gnashing of teeth as some think, or would have you believe.

With an external HD, a Mac mini, PureMusic, and an iPad, I’m enjoying the heck out of my setup and 28,000+ tracks – redbook and HD’s.

From my current and obvious audio standpoint, my past, present and future state-of-the-art audio software is USB PC audio and vinyl.
I agree with most here who suggest that your USB interface was the likely culprit. I'm not familiar with the DAC you were using but IME most DACs with multiple input options have a severely compromised USB input. If you are dead-set on USB you should look at a standalone asynchronous USB DAC. This is what I am using at it beats the pants off of my previous CDPs - including SACD/DVDa on more expensive machines. In fact I used to have the very same Sony player you do and my Mac Mini --> DAC is so much better it is laughable.

Another thing to watch out for is to make sure your software player is transmitting a bit perfect signal to the DAC. Itunes alone is a no-go, you need aftermarket add-on software.
As for software:
JPlay, a kernel streaming driver and hibernate mode.
Some say win8 is best but haven't tried that yet.
Spectron wrote: "It could be much cheaper if USB output from a music server will be well designed and well executed, if music server designer would asume that USB DAC input is mediocre and do THE RIGHT JOB on the side of music servers."

I'm afraid not. The master clock is still inside the USB interface in the DAC, not in the server. It's the USB interface in the DAC that matters.

Steve N.
Empirical Audio
EMM Labs DAC2 USB port was designed almost 5 years ago when computer audio was at its infancy. Its USB port was almost an after though, and only capable of running 44.1kHz or 48kHz only and very likely used a synchronous USB connection (par for the course of that era).

The real beauty of that DAC would not be fully realised with the USB port. You should see a big improvement going to an asynchronous USB-SPDIF device like Wavelink HS, or Berkeley Alpha USB which also support Integer/Direct Mode with AudirvanaPlus on the Mac platform, and hooking the SPDIF to the coax/AES input on the EMM Labs DAC2.

You will find a marked improvement too if you use a dedicated computer that runs without the multiple processes running in the background. You will also find that stuff that improves hifi components (power supplies/vibrations) will also have an effect on your PC audio. There are linear power supplies, Solid State drives (no vibrations) that can be used on modified or custom built PCs/Macs.

That said, I find that spinning a disc still sounds marginally better than computer audio but with the leaps and bounds of computer software and technology, it's much closer today than it ever was.
Hfisher3380, I am not dead set on the USB per se. I will be perfectly happy with an interface from the computer (PC/MAC) which is reliable and gives best audio output without any compromise.

With true asynchronous transmission the DAC is remarkably immune to jitter because a buffer in the DAC controls the flow of the data. The DAC controls the audio transfer from the computer, ignoring the computer’s USB bus clock and instead slaving the computer to the buffer in the DAC. The DAC requests the packets of audio data from the computer and stores this data in the buffer. The DAC’s buffer and the digital converter chip itself are then sync’d with a single fixed-frequency clock. This method assures a irtually jitter-free transmission.
Top, have you considered any networked player type devices? I use Squeezebox Touch currently, which is unfortunately no longer in production, but there are others. I used older technology Roku Soundbridge prior. Both performed similarly well via the same external DAC. Other current similar devices may as well. Wifi connection helps keep stereo and noisy computer isolated. A pretty optimal architecture for computer audio IMHO.
Anything other than a really good networked player or good USB interface will be a compromise in SQ.

Other interfaces can be reclocked however, to reduce jitter. The artifacts of upsampling are audible, but not bad given the latest technology in upsampling.

Steve N.
Empirical Audio
Mapman, No, I have not used any network device other than Windows laptop and MacMini. Wifi is an interesting option. At the time I thought the wifi is inferior to wired connection for HQ audio, even though it can isolate the computer noise. Probably I have to revisit this option again.
Can anybody suggest me a good network server with wifi to consider ?
Topmostaudio: Inteface Converter, by itself is not revolutionary step. There ara companies which produce them for years under different names e.g. PS Audio, Linn etc and their sound quality vary.

Today, IMO, is much cheaper to produce very high quality music servers utilizing such brilliant processors as Intel "Haswell" i7 where I can sacrifice, say 1% of its power on useless activity and use 99% on music (depending, of course, how well I deal with operating system, high freq grounding noise etc etc).

If I would design similar quality "Inteface Convertot" from the scratch then to get "there" - it will cost you money which, TODAY, you will never pay. This reality forces us, in Musica Pristina, to excell (as best as we can) in music servers where we can match our technology e.g. PSU and off-the-shelf processors like Intel "Haswell"

The maojor question, I, as the end-user in search of turntable or "Interface Converter" or tube preamp ask myself - how it sounds? The particular design philosophy is much less of my concern.

Audioeng: the same answer is to you. if DAC is "garbage" (and if it has poor clocks then it is GARBAGE without going any father, don;t care about it magic tube output stage or whatever) then no music server, USB Interface etc will help it.
"Audioengr: the same answer is to you. if DAC is "garbage" (and if it has poor clocks then it is GARBAGE without going any father, don't care about it magic tube output stage or whatever) then no music server, USB Interface etc. help it."

Actually not true. The DAC S/PDIF input will not have ANY clock in the DAC associated with it UNLESS it has a hardware upsampler chip or other PLL to reclock it.

Even with or without the hardware upsampler, a low-jitter USB converter will make a HUGE difference, even with an inexpensive DAC. This USB converter will have a good master clock and drive the DAC using a good S/PDIF coax.

The master clock jitter is more important than the DAC.

Steve N.
Empirical Audio
@Spectron, have you heard an EMM Labs DAC2?

It is a pretty damn fine DAC. It's one of the reasons I broke my own budget and bought the XDS1.

It takes time to get everything right. You need to optimize the computer OS for audio play. Not all computers sound the same. I have a friend that built 2 computers and one of them sounded awful. So you have software and hardware to get right on just the computer side. You also need a good USB converter they are not all created equal. I can tell you in my opinion and with my hardware Windows Server 2012 sounds amazingly better than optimized Win 7.
You should be able to beat the sound of a Sony 5400 as I owned one a couple of years ago.
Can anybody comment on Lynx HiLo converter with USB input ? Is the USB implementation truely asynchronous ? How is the DAC performance ? How would it compare to a good USB/SPDIF converter + EMM DAC2 ? Thanks,
Doggiehowser: To my regeret I did not auditioned EMM Labs DAC2. However, knowing reputatio of the designer you probably cannot go wrong with this choice

Audioeng: Lets not play with words, please. Typical average DAC has PPL i.e. as the rule, it has clock(s).

For music lovers who own DAC with SPDIF inputs only - your and very, very few others USB inteface plays enormously imprtant role - allowing these audiophile to continue to use their DAC and, as you said, frequently improve sound quality over "raw" SPDIF directly from the server. Your device is great, particualrly with its dedicated PSU
I think anything other than an spdif out via a sound card is a LARGE reduction in sound quality. Why would we go through the abomination of converting a usb signal into high end audio when you can have sound card doing it natively? USB in music is like flying to sweden for a sex change. Why go through such a drastic conversion? (because they can sell it easilly to everyone! - Techno phobes need not be concerned)

Today, I am seeing more and more people abandoning (finally) USB. They gave us usb because it was idiot proof - every puter has one and the user didn't need to open up the box. Well, great things usually take some effort. My dealer actually laughs when we discuss USB as an interface. I laugh as well.
Shame, Cerrot. Having the sound card in the computer just means it is susceptible to the EMI/RF noise that is in the computer.

USB provides a form of isolation from that noise.

Other options include what say Aurender has done which compartmentalizes the computer's components noisy sections which work just as well. But then you'd have to customize a completely new computer motherboard, power supply etc. Something few people have resources to do.

The closest you can achieve if you are building a music computer, is something like CAPS, and there're still benefits from USB.
On topic. How important is the Analog section of a DAC and what affect does it have the perceived performance of the device?
08-24-13: Cerrot
I think anything other than an spdif out via a sound card is a LARGE reduction in sound quality. Why would we go through the abomination of converting a usb signal into high end audio when you can have sound card doing it natively?

I am going through this mental debate right now as I plan my CAPS server build. My practical side says why not just get the ASUS Xonar soundcard and use its SPDIF straight into my DAC instead of having to get USB converter in between. As Doggiehowser has pointed out there appears to be come benefit to using the USB then a converter to get rid of noise, jitter, etc. That being said, I am going to have to try out both ways to see which is better.
I have the ESI Julie@ soundcard; didnt hear the asus -
I never heard of isolation being a benefit to USB; if anything, the 'isolation' creates its inherent problems.

USB was created to hook up peripherials, not to play muic.
The puter is definitely susceptable to noise but it is much easier to deal with than the USB interface's susceptablity to crappy sound, jitter, and the rest. I added a nice power cord, richard grey power conditioner, shatki stone on top of the case and nice isolation feet. the puter has silent fans (for now) and is in the next room. It sounds awesome (but not as good as a VERY good CD payer into the same dac). I have heard the Ayer USB converter and th Berkeley and neither (to my ears) sound anywhere as good as the soundcard. I plan on building a caps server as well, but it will have a sound card. There truly is no practical explanation as to why you would not use a sound card, or at least try it first. Considerig the soundcardis $150 and the usb converter is $2,500, why not just try the sound card?
Vegas - The analog section of the DAC is very important to achieving balance, dynamics and an analog quality. Detail, imaging and slam are mostly a result of lowering jitter in the digital sections.

Important analog aspects are:

1) output drive current capability - output impedance and linearity with dynamics
2) I/V conversion linearity
3) gain stage(s)
3) volume control technology, if included

All of these 4 can be compromised, resulting in compression, low S/N ratio and anemic dynamics. This usually occurs with Op-amps, slow-reacting power subsystems and poor volume control technologies.

The best course is to avoid op-amp outputs IME. Also, try to eliminate the preamp altogether or replace it with a transformer passive linestage.

In order to achieve the best system S/N ratio, it is optimum to make the signal as large as possible early in the chain, as in the first stage after the I/V conversion or the I/V stage itself.

Steve N.
Empirical Audio
Steve N: i disagree with your statement "If you want to not only beat, but exceed the performance of the very best CD transports/players, you will need to use USB.

my PWDII/Bridge/PWT has "exceeded" every USB set-up i've heard to date. and i'm not talking bargain basement USB setups. i do stream alot...but have a WES610N pulling in the stream and wiring it to my gear. works beautifully and sounds fantastic. jitter is not an issue for everyone....if you have the right gear.

you don't "need USB" to get outstanding sound. there are alternatives.

no...i'm not an engineer or anything even close. i do know a thing or two about what sounds good.....and it doesn't all revolve around USB (like you make it sound sometimes).
Levy you aren't wrong but most other DACs don't have a network lens bridge connection.
Levy - this may be your experience with a limited number of USB interfaces, but they vary across the map. I have customers with your PWDII/Bridge/PWT combo and they are still using my USB interface, the Off-Ramp 5 because it is better.

Steve N.
Empirical Audio
Today, I am seeing more and more people abandoning (finally) USB.
Examples? Because I'm seeing just the opposite.