Any insight with the Berkeley Alpha DAC ..??

I'm not technically knowledgeable about computer audio, so I'd like some help understanding why Reference Recordings recommends the use of a sound card in the playback equipment (BTW, I own a number of RR CDs and am glad it is back in business).

From what I know, the original sound cards were an all-in-one device that first converted the digital data from the hard drive to SPDIF and then converted the SPDIF to analog. It may have even amplified the signal after the final conversion. The sound card also took the SPDIF feed from the CD-ROM and converted it to analog. The net result was that speakers were the only sound equipment external to the computer needed for playback.

Audiophiles rejected these sound cards in favor of external conversion devices because (1) the noisy electronic environment inside the computer created distortion, (2) sound cards were cheap devices made to a price point to sell as part of the computer package and (3) sound cards limited the type of sound produced and external DACs did not. As I understand it, quality computer audio systems bypass the sound card for conversion to SPDIF (and therefore for conversion to analog too) by taking the digital feed from the hard drive outside the computer. If this is so, why is it necessary to use a “high quality” sound card or any sound card at all? Does the sound card perform some other functions that require very high quality parts or sophisticated design? Or does the Berkeley Design Alpha DAC perform only the conversion to analog, leaving the conversion to SPDIF to the Lynx AES? If so, why not substitute a good quality USB DAC for the Berkeley?

Steve,

Thanks for your response to my question. I haven't been back to this thread for a few days, but if your still around maybe you can clarify something for me.

You said:

There is no direct S/PDIF from a computer.

I take that to mean that you cannot extract digital information from a hard drive in S/PDIF format - it is first extracted in a different digital format and then converted to S/PDIF. My question is, where does that conversion take place and does it require a sound card? If you are saying that the conversion to S/PDIF must occur inside the computer, with the assistance of a sound card, then what does a USB DAC do that is different from a normal DAC? I was under the impression that a USB DAC converts the computer's digital format to S/PDIF as well as convert S/PDIF to analog, but I'm not really sure. Even if my impression is correct, maybe the sound card "sets up" the conversion to S/PDIF by performing some necessary preliminaries, like clocking.

I want to get the basic steps straight before tackling the details of implementation.

Update to my last post. Just read some other computer audio threads that suggest that the designation "USB DAC" refers to the way digital information moves from the computer to an external DAC, not any extra conversion that takes place in the DAC. Does that mean that the conversion to S/PDIF must take place inside the computer or could the computer's digital information be transported outside the computer in a format other than S/PDIF and then converted? Hope the other readers of this thread will excuse these plodding questions, but there's very little information available that spells out the basics in a clear, step-by-step way.