If you're one of those people in search of the holy grail of audio fidelity, there's no doubt that using a PC as a complete front-end solution has probably crossed your mind at one time or another. Saving your entire music library to a hard drive and having all your favorite tracks just a few clicks away is certainly appealing, but what about the sound playback quality? Can it compete with dedicated disc transports costing thousands of dollars?

If you haven't made the move to using a PC as your front-end player, perhaps you've been deterred by the fact that PC's lack the dedicated audio engineering that we find in high-end disc spinners. Or, like me, you brought a cheap CD player and modified it to the nines and are now reluctant to invest your time in starting afresh. Such was my case until a couple of months ago when my aging Pioneer PD-S801 gave up the ghost, leaving me scrambling to find a suitable replacement.

I'd invested so much time into the PDS-801; just about every aspect of the machine had been changed somehow. Modifications to the unit included a directly heated triode output stage, fitting a low jitter master clock, replacing all audio critical electrolytic capacitors with ultra low ESR types, and replacing the stock power circuitry with ultra low noise wide bandwidth voltage regulators. Most of the inspiration for these modifications came from cruising DIY audio forums, where other obsessive-compulsive audio crazed folk like me tend to hang out.

Frequenting such places again in my time of need, I noticed that the buzzword in audiophile circles regarding ultimate digital playback now revolves around using PCs to store and playback music rather than the very best standalone transports that money can buy. It seems the buzz is primarily about three things. The first is the prospect of bit perfect data retrieval when using a suitable lossless format to burn your compact discs to a hard drive. The second is using DRC (digital room correction) to help compensate for listening room resonance and reflections. The third, using software based digital crossovers, thus overcoming passive crossover insertion losses and allowing for a more cohesive integration of drive units in multi-driver speakers.

My previous experiments using a PC with mid-budget consumer grade soundcards fell short of providing the resolution, sound staging, and detail retrieval of the modified Pioneer player. I'd put the differences down to the rampant levels of noise present inside of a PC case. After all, when it comes to soul-stirring audio reproduction, ultra low noise clean DC power is a must, and that's not something that we associate with your typical computer PSU. Computer PSUs are primarily designed to supply huge amounts of current on demand, within a certified noise band of course, but nowhere near the quality we find in a dedicated linear power supply. Hence, serious audio playback requires a soundcard designed to deal with the shortcomings of the PC's internal environment.

This leads us back towards pro audio gear used by recording engineers such as the M-Audio and Lynx range of soundcards. Most of the physical differences between pro audio solutions and your basic consumer oriented product can be put down to better components, trace routing, voltage regulation, and power supply decoupling. In addition, the pro cards feature low latency drivers that bypass Microsoft's K-Mixer and can be used with specialized software allowing all sorts of signal rerouting and manipulation. This adds up to making the pro audio offerings flexible enough for people wanting to engage DRC in a fully customized multichannel setup.

Although user reports on some of the internal pro soundcards are very favorable, my interests are stoked by external affairs. An external box presents far more interesting possibilities and flexibility to me when it comes to power supply and output stage modifications. Both are things that I'm too twitchy to leave alone and unchanged until the unit either dies under the knife or gives me what I want in terms of sonics.

One such solution revolves around using the Texas Instruments 270* range of USB - I2S and S/PDIF converter chips, which are used in several commercial outboard DACs that are rumored to be capable of upstaging even the most expensive standalone players. Better still, a range of attractively priced DIY DAC kits based on the Texas Instruments receiver chips are available that utilize levels of engineering found in commercial products costing much more. The unfortunate upshot with the TI 270* family of converters is that they're designed for two-channel use only. Those demanding external multichannel audio units will have to look towards Pro FireWire audio boxes or standalone units like the Behringer DCX2496, which has more functionality than most of us will ever need. If two-channel playback is sufficient then Logitech's Squeezebox music streamer also deserves a mention. Both the DCX2496 and Squeezebox are products that have been thoroughly adulterated by DIY masterminds and there are plenty of commercial or DIY modification packages available for both units that elevate their performance.

We aim to put some of these products to the test in the coming months while also focusing on commercial loudspeakers, disc players, and amplifiers for a range of budgets from pocket friendly to the spare-no-expense league. Today, we will take a brief look at two DIY DAC kits that we've built up and have been subjectively listening to for the past few weeks. We'll also be looking at PC-based DRC in the form of a software package called Audiolense 3.0 using some open baffle single driver speakers from 3D Sonics. If any of this tomfoolery interests you, read on....

The Test System
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  • notanakin - Wednesday, December 3, 2008 - link

    Generally I found the article interesting, but why on earth was Vista 64 used for the review? The author admits he couldn't find USB-ASIO drivers, and that ACXO doesn't support Vista 64 properly. Surely first you check what would be interesting for the review and then choose an appropriate OS? Also, I'm pretty sure that Vista 32 or Win XP are far more likely to be used by most readers of the article.

    Thank goodness he wasn't running Win ME on his PC.
  • milosz - Wednesday, December 3, 2008 - link

    Single Ended Triode amps add a considerable - and DEMONSTRABLE- amount of low number even-order distortion to reproduced sound. To their devotee's, this sound is "full," "rich," "harmonically complex" - etc. But what they're hearing has been ADDED by the electronics. If you listen on speakers like the single-cone types used in the review, adding some additional harmonics to the overtone structure can compensate for the lack of upper treble and poor transient presofrmance of these single-driver systems. These single driver systems store a LOT of energy in the low treble- just look at their waterfall plots. When the signal stops the cone keeps moving, from the high mass storing energy. A ribbon tweeter has a moving mass of 0.01 g while a single-driver speaker like these has a mass of about 10 grams. You tell me which will be able to faithfully folow the motions demanded of complex high frequency reproduction, and which one will have some much inetria that it will keep moving long after the signal has stopped. But if you use a SET on these things, it generates a lot of extra low order even harmonics to sweeten things up - it masks the problems introduced by the speaker to some degree.

    I think it preferable to use electronics that add as little of their own coloration as possible. That's why I try to use the best electrostatic or ribbon speakers I can afford, with the best class-A amps (tube or solid state, a good amp is a good amp) I can afford, as well as high-slope digital crossovers and top-notch D-to-A converters. I've also tried some SACD and DVD-A audio and frankly it doesn't sound any different to me from CD. Vinyl also has a lot of good music in it if you can tolerate the light hiss and crackles that even the best vinyl playback has. Of course the thing I've spent the MOST money on is the MUSIC. For a n old guy like me who has made a little dough, $75,000 for CDs and LPs, $25,000 for a 2-channel audio system is about the right ratio.
  • Carnildo - Wednesday, December 3, 2008 - link

    I noticed one word missing from this review: "double-blind". To evaluate something as subjective as audio quality, you need to do double-blind testing to make sure the results aren't being influenced by your expectations of what the sound should be like.

    One thing I'd like to see is an all-digital sound system: the sound is read off the disc, converted to 64-bit floating point, processed for playback (mixing, volume adjustment, room compensation, frequency separation if you're not using full-range speakers, etc), sent out over the wires still digital, and then converted to analog just before it hits the coils in the speakers. Keeping it digital will avoid most noise sources, 64-bit floating-point will give you a noise floor far below what anything analog or integer digital can manage, and you've got the full processing power of a modern computer to adjust for things like an imperfect room layout.
  • RagingDragon - Saturday, December 6, 2008 - link

    Floating point leads to rounding errors, and processing the floating point signal would increase those rounding errors. Todays top DAC/ADC are mostly 24-bit (unsigned) integer, so using 32 or 64 bit integers would be a more than sufficient, and without the rounding errors inherent to floating point math.
  • headbox - Wednesday, December 3, 2008 - link

    So you tested audio in a bare room with hardwood floors. Hardly a room for an "audiophile."
  • strikeback03 - Wednesday, December 3, 2008 - link

    IMO that is the kind of thing they should focus on - what can be done with computers to get the best sound possible in normal rooms? Kinda like Anand's home theater, music rooms are interesting tech but not something most people have the time, money, or space to implement. So what can be done to get the best sound in a dorm room, or multi-purpose family room, etc.
  • pcfxer - Tuesday, December 2, 2008 - link

    "One of the chief perpetrators of this revival was a fellow named Throsten Loesch. "

    You mean Siegfred Linkwitz, yes?

  • ccd - Wednesday, December 3, 2008 - link

    Sigfired Linkwitz has been a major proponent of dipole speakers, not open baffle speakers.
  • ccd - Tuesday, December 2, 2008 - link

    Like many here, I think the DRC discussion is best suited for a website like Anandtech. As for some of the other issues, I highly recommend that you visit www.linkwitzlab.com Not only is the Orion the best speaker that I have personally heard, but Sigfried Linkwitz is an engineer who designed a line of very well reviewed commercial speakers. At his site, you will find a number of papers written by him on speakers and how we hear. You will find some good science there, not snake oil or myths passed among audiophiles as truth. You will find that the speakers he offers at his site as well as the literature there runs counter to many of the assumptions made by this author.
  • royboy66 - Tuesday, December 2, 2008 - link

    Now to the meat of this audio is not something we know everything about -battery power isolates all power line noise if done properly, tube amps and tube microphones and recording equipment -when properly maintained have made magnificent lifelike recordings -i have many of them -close your eyes and you are there! I have a large hifi collection and had 19 amps at one stage -i got sent over a mint 1966 Fisher X10D valve amp owned by a guy who looked after it -original box, valves everything and maintained by a valve technician –it had not had a hard life – i never ever thought it was going to sound any good hooked it up and nearly fell over the sound was alive –i sold almost all the amps i had after that experience –they were sterile crap! I still had some very fine solid state though eg Electrocompaniet for example and it too made beautiful music .Now you guys who just blast your ipods at 120db in your ears have no idea about sound quality –if you know anybody passionate about audio go listen to their setup –chances are it will sound great because they have put the effort in to make it so. I do not believe in voodoo or bullcrap –but never underestimate power line noise and rf contamination etc
    Also i can comment on speakers and dacs –they all make a difference –if i ever have to listen to a tda1543 again it will be too soon !the cymbals sound dull because that dac is barely 15 bit in quality –would you use a commodore 64 now to surf the net – of course not. This dac is so far outdated it is not funny –listen to cymbals on a good record they do not sound like the tda1543 reproduces them –it simply does not have the resolution in the mid to upper frequency to sample properly the lifelike sound of a cymbal –but the other did because it was a better computer for those same frequency
    I have as one of my system the NHT XDA digital active system –are we supposed to believe it is the last word in audio because it is digital and has one of the flattest responses irrespective of room –it basically does not need that. I asked a few friends how they thought it sounded compared to my 20 year old Infinity Kappa9 and not one of them liked it over 20 year old speakers driven by valve or solid state. what does this mean? –there is more to audio than we think –so guys keep an open mind and hopefully through these articles we will end up with great computer sound –i personally at the moment use a squeezebox with lossless Flac and or digital out to it or a city pulse dac11 for computer audio –amongst other options
    Pc noise is definitely the big problem – i live in the country it is quiet so my background noise is lower and the pc is loud –totally silent or in another room is the go –but my power is crap due to being in a rural area –hence i say if everything could be run off battery or solar it would make a big difference –listen to Jack Johnsons solar powered album –how good does that sound –awesome! Lastly guys I am no audio snob –i have no car but plenty of audio equipment and cds ,records, dvdaudio, sacd, upsampled music etc – i get given bucket loads of mp3 and use that to find music worth listening to –the pc can and is going to be the source of quality music for the future so let the articles continue

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