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....