This is a great conversation and I'd bet it has been read by many looking for the right solution for PC SPDIF out.
Ultraviolet/Rsbeck's gon posts about the M-Audio Audiophile (USB, firewire) have made me skeptical of the unit before it arrives on Wednesday. The PC digital out is the last piece in my system and has been the most difficult to choose. Here are the most important things I have gathered:
1. The M-Audio Audiophile USB using SPDIF digital to external DAC at least sounds different (and reportedly worse) than other units such as the Waveterminal U24. I haven't found any direct comparisons with RME or SoundDeluxe. All I've read about those are they are recommended. You can get a used RME card with SPDIF for about the same price as a USB Audiophile.
2. The piece matters! I'm going to re-post Dmitrydr's comment. If true, this seems to be the most important thing to know about buying SPDIF out for a PC: "you'll need a box (where jitter will inevitably appear) that accepts USB data flow, and converts it to SPDIF, i.e. performs quality reclocking, etc. Here, if this box is treated just as part of the audio system, and connected with short good SPDIF cable to the DAC, there should be less jitter then from a normal CD player. However, for low jitter this box must have audiophile-grade power supply, oscillator, and other parts, so its price level must be expected somewhere near any other audiophile DAC. Cheap solutions must introduce lots of jitter, making the whole idea nonsense."
3. The Waveterminal U24 is capable of not re-sampling 44.1 CD audio which may account for its truer sound (but no one seems to know for sure).
Oh, and Hbrandt -- you got me interested in this reclocking business with the Apogee Big Ben comments. Please convince me not to spend another $1k on it or I probably will ;-)
