Audiophile USB to PCM

Harry, you are trying to do what I do, and the PCM conversion is necessary. I'm using an Edirol UA-1D right now, which has a USB dongle on one end and a connector for coax PCM out on the other. Nothing else, no DAC. Sounds good for background music running into my Theta (I'm using mp3s compressed with -alt preset extreme, not uncompressed AIFF/WAV/AAC). I believe the Edirol is limited to 16/44.1. Since USB is an asynch protocol, I believe there should be no USB induced jitter in such a setup. Not sure what RSBeck's set up was with the M-Audio, but I previously used a Sonica from M-Audio to do USB to PCM conversion (the version I had was not equipped with a DAC) and it sounded fine.

Onhwy61:
Technically, I believe you are correct. The files on the hard drive are PCM, but they must be converted to a stream that can be read by a dac. I believe that there is a header that is stripped from the stream...and then, yes...it is simply a pcm bitstream. It is not a conversion per se...and I shouldn't have referred to it as such.

Bottom line is that I want to get tunes from my laptop to my sound system. I'll leave the specific terminology to the computer gurus.

harry

I decided to go with the Waveterminal U24. My understanding is that it is very well made and will provide a bit accurate stream with no conversion from 44.1 to 48k. I'll report here what I find.

Thanks to all for your kind help.

harry

Here's the Edirol piece to which Ed is referring. This is the reverse of the piece I posted before, which means it is what I thought the other piece was. It will take a USB connection from your computer and convert it to SPDiF or Toslink, keeping the signal in digital. But, nowhere does it say it converts the signal to PCM. I'm not sure where this is coming from. My understanding is that the computer puts the signal out in digital at whatever resolution you imported it and I don't know that it needs to be "converted" to PCM nor do I see that the Edirol piece performs this function. I'm not sure what the problem with the M-Audio piece wasm either -- but -- I can tell you that when I was running MP3, the pieces in my system were not critical. I could take a feed from the headphone out, split the signal into L & R, feed it into analogue inputs in my pre-amp and you couldn't tell much difference. Now that I import my CD's uncompressed, you can tell large differences between, for example, the M-Audio piece and the Apogee.

http://www.edirol.com/products/info/ua1d.html

The Waveterminal piece is interesting. It offers sample rate conversion. Maybe this is what is needed to take the signal from the computer to a home audio DAC and maybe that is what was missing from the M-Audio piece. Like Harry, I am no computer expert, I learn as much as I can in order to get the computer to do what I need, but my interest lies far more in music, which is the carrot that leads me to learn about computers. I am curious to find a product that will let me connect the computer to the digital input on my pre-amp so I can use the DAC in the Proceed, so I will be interested in hearing about Harry's experience with the Waveterminal piece. I the meantime, I am getting a real kick out of this G4, Apogee, Mackie system I've built. It is surprisingly accurate, musical, and enjoyable. But, this has opened up a little mystery and now I am curious to know whether uncompressed music files like AIFF need to be converted before they can be read by a home audio DAC and why my Apogee DAC doesn't need any conversion before it can perform its magic.