As more audiophiles dip their toes into computer-based audio they discover, to their dismay, that it's far more complicated than conventional audio. In fact, the level of complexity involved in even a basic computer audio system dwarfs that of the most baroque multi-amp, multi-crossover, multi-driver traditional audio installation. Why? In computer audio the hardware, software, and cables interact with one another to affect the sound. Two very similar setups can sound different merely because particular details of their configurations are different. Unfortunately even small variables can have substantial sonic implications. Going from a 3' USB connection to a 6' one is audible in some systems. While this may be a tweaker's paradise, it's a reviewer's and manufacturer's nightmare.
In conventional audio it's relatively easy to substitute one component for another in a reference system and get an accurate impression of that component's intrinsic performance. In computer audio the complicated interrelationships between different parts of a system make a clear assignment of sonic characteristics far more difficult. Generalizing that a particular interface is better or worse than another can't be ascertained by merely doing A/B tests in a handful of systems. There are simply too many variables at work to be able to make these kind of broad statements about universal performance.
In an effort to try to clarify what does and does not make a sonic difference in a computer-based audio system, let's look at some of the basic building blocks of computer audio. The goal here is to give you a better idea of what's important and what to look out for when you assemble or make changes to your own computer-based audio system.
I'm not going to delve into the whole PC versus Mac issue here. Both systems have unique advantages and disadvantages. But whichever you use, both suffer from similar inherent problems related to properly matching software with hardware to attain optimal performance. My goal here is to educate you about the parts and pieces, not to recommend universal solutions.
You might assume that getting the fastest, most powerful computer processor available is always the best way to go for a computer music system, but this is not the case. If you have a dedicated music computer whose sole function is reproducing music you can use a less powerful processor without experiencing any sonic degradation. Many computer-music experts recommend or use the lowly Mac Mini as the center of their state-of-the-art computer music systems, while others use fairly basic no-name PCs.
What is far more important than processor speed or power is whether your processor can and will support the latest generation of software. For anyone putting together a Mac system, it's better to have an Intel-based Mac that can use the latest Snow Leopard operating system than a more powerful, earlier-generation computer with a Motorola processor. The newest $599 Mac Mini trumps any G5 desktop for music-system use. On the PC side, having a unit that will run the new Windows 7 operating system should be a real advantage since this new version of Windows promises a more streamlined audio-processing chain than the ones currently available on Vista or XP systems.
A universal fact, regardless of operating system or processor, is that more RAM is always better. Although I'm not fond of generalizing, I'll go on record as recommending that you should always install as much RAM as you can afford and as your processor will allow. Maximizing RAM minimizes disc-caching (when a computer writes and then reads data from the disc in lieu of keeping it in RAM). And why is writing and then retrieving data from a disc so bad? Because each time data is copied by being written to a disc and then read off that disc it increases the likelihood of data errors and timing errors that degrade sound quality. Disc-caching also slows down a computer's operation and processing efficiency. So, disc-caching is bad and maximum RAM is good.
Data requires storage--you need a place to keep all your music files as well as the files used to run your computer. Most computers use hard drives for this purpose. Faster drives with larger on-board memory caches and higher rotation speeds are better for computer-music systems because they deliver data more rapidly and have more memory for error correction. Whenever possible, 7200 RPM drives are a better choice than 5400 RPM drives.
Recently silicon memory discs have become more readily available and competitively priced. These silicon static-memory drives use less electricity and generate less heat than conventional hard drives because they have no moving parts. For some applications, such as storage of digital music files, they are superior to conventional hard drives since they have faster access times and lower numbers of read errors. But in situations where data must be written, retrieved, and rewritten over and over again, such as in your main computer drive, silicon discs aren't the best choice. Silicon drives have a finite number of times that they can be successfully written and erased without write errors increasing. In short, silicon drives make excellent data drives but not optimal operating drives.