Computer Audio 101: Revving Up a New Spin for CD Playback

For years now, hobbyists have been transforming their computers into audio source components, a natural endpoint for all kinds of digital music.

Conceptually, it's quite simple—store, instantaneously access, and manage an entire library of music on your computer. No more sorting through piles of CDs. Yet, serious audiophiles (especially those not computer savvy) have traditionally been hesitant to embrace this "techno" alternative to their tried and true CD players.

They should take a new look, as the computer can be the powerful audiophile device.

Enter iTunes and the iPod.

While initially seen as a bane to high-quality music reproduction, Apple's user-friendly interface gets regular people (not just computer geeks) into the game.

This "killer app" largely addresses the computer fear factor, but many in the high-performance audio world remain skeptical due to the highly compressed MP3 downloads with which those programs are associated.

They also chafe at the limits on duplication enforced by the DRM (Digital Rights Management) present on most downloaded music files.

Add in the fact that the inside of a computer (with its multiple fans, whirring hard drives, switching power supplies, digital clocks, and magnetic fields) is a less-than-ideal environment for attempting high quality digital-to-analog conversion and embedding a refined analog output stage, and such skepticism appears meritorious.

That is, until about four years ago, when a few very smart audiophiles began to shift their opinions and recognize that previously perceived limitations can be overcome with actual performance advantages extracted from a computer audio platform.

Not only can uncompressed, bit-perfect copies of CDs be ripped to the computer and then managed by iTunes or similar file management programs, but those functions most critical to achieving high-performance results (i.e., the digital-to-analog conversion and analog output stages referenced above) can be isolated and given dedicated focus by removing them from the computer itself and ensconcing them in a separate component connected via a USB or Firewire umbilical.

All of a sudden, opportunities for savvy designers to apply their high-performance audio principles (e.g., linear power supplies, superior wire and componentry, resonance control and layout, chassis design) abound in the hunt for great sound.

The results are apparently so good that many now espouse that, once decoded, the bit stream coming off a computer's hard drive sounds even better than that taken from the spinning CD on which it originated.

One audiophile with whom I corresponded actually replaced his DCS stack (the famed Verdi, Purcell, Verona, Elgar+, four-box CD/SACD player clocking in at just under $40,000) with a MacBookPro and a Wavelength Audio Crimson (starting at $7,500 in its basic configuration), and has never looked back.

The high end has certainly taken notice, with a bevy of stalwarts (e.g., Audio Research, Ayre, Linn) beginning to actively support the computer audio fray by designing digital analog converters dedicated for computers and/or expanding the connectivity options of their multiple-input DACs to include USB, Firewire and/or Ethernet. Claims of superior sound, coupled with the notion of flexibility of the "server" concept, made me realize it was time to investigate the situation for myself.

What's Wrong with the CD Player?

CD players have come a long way in the twenty-five years since their debut, but really only start to get serious (from a musically engaging, high performance audio perspective) at about $3,000, and are rather "limited" in their capabilities.

One might say that CD players are stuck in a rut. They have a singular purpose: spin one particular type of disc, extract one specifically formatted digital bitstream complying with "Redbook" standards, and convert the same into the analog domain.

From a sound-quality perspective, CD players can only do so much due to the inherent limitations of the underlying format which is, at best, mediocre for sound reproduction.

Such "mediocrity" is not intended as a slight to the format initially released with claims of "perfect sound forever." Rather, it's a historical fact given the specifications for the Compact Disc.

What has become known as the "Redbook" standard is based on the red cover page of the Sony/Philips format specification manual that dictates, among myriad other things, a bitstream of 16-bit data sampled at a rate of 44.1 kHz.

These standards were established when available bandwidth was only a trickle compared to what we have now, and the "large" hard drive option on an IBM AT computer offered just 32 megabytes. In reality, it is rather astounding that the Compact Disc as a format, burdened with the nascent digital capabilities of the early 1980s, holds up as well as it does.  

By contrast, a computer (with outboard DAC) presents a platform with an "open" format, and allows for an ever-expanding capacity to store, manage and play different, and truly high-definition digital bitstreams (e.g., 24bit/96kHz masters).

While proponents of computer audio applaud the expansive capabilities on offer, the threshold question for me focuses on this–can a computer audio set-up linked to a high-performance outboard DAC enhance the enjoyment (both qualitatively and quantitatively) of listening to my expansive CD collection?

Putting it Together

After picking the brains of several industry gurus and surveying on-point forums (e.g., computeraudiophile.com and audioasylum.com), I settled on using an Apple MacBook ($1,099). I'm not much of a computer guy myself and had never even used a Mac (it's always been a PC at work), but the MacBook satisfied my three primary requirements.

First, I wanted setup and operation to be as plug and play as possible to compete with the inherent simplicity of a CD player. (My inexperience with the Mac and iTunes also seemed a pretty good test.)

Second, with its integrated screen, keyboard and hard-drive, the MacBook presented the self-contained, compact footprint I needed (I just couldn't stomach the idea of a computer dominating my equipment rack of high performance audio gear).

Finally, by using the battery power available on a laptop, I could avoid introducing switching power supplies into my listening room, something about which I've been very careful, as switching power supplies can have a negative impact on an audio system's performance.

Next, I turned my attention to the outboard DAC. With plug and play in mind, I only considered DACs with USB or Firewire compatibility. Available solutions begin for as little as a few hundred dollars, such as the Cambridge Audio DacMagic DAC, a $400 device featuring coax, TOSLINK and USB inputs, or the Apogee Duet, a $495 Firewire device targeted to musicians.

However, for the truly high-performance approach and results I was seeking, I knew I'd need to investigate offerings in the $1,000 range. At that level, there are quite a few well regarded USB DACs, including the Benchmark Audio DAC1 USB ($1,275, you can read a review here), the PS Audio Digital Link III ($999), and the Wavelength Audio Brick ($1,750).

Nevertheless, after kicking a few tires (and to provide my computer audio experiment a fair shot at matching the sonic benchmarks set by my reference CD players ranging from $3,500 to $8,000), I decided to go a little further up-market and, in the end, arranged for a month-long test of the Wavelength Audio Cosecant ($3,500 in current Mk. III format), and the Weiss Audio Minerva ($4,950). While both units offer high-end pedigrees, each takes a distinct approach to the task at hand.

On to the reviews...