Best soundcard if have outboard DAC


Looking to use a PC as a transport. Will have an outboard DAC feeding a preamp. I want the soundcard to feed the DAC with a digital signal. I don't want the PC/soundcard doing any processing, only sending the untainted digital signal to the DAC. Sound is important, not cost. What is the best soundcard for this? Also, what is best: AES/toslink/USB?
bigamp
You can use the Cmedia 8738 based sound card to output the 44.1 signal to the DAC. About 10.00 dollars at the store.
If you've got an outboard DAC and the USB to get to it, as far as I understand it, you're bypassing the onboard soundcard entirely -- so it shouldn't matter what it is (or whether you have one at all). Perhaps I'm missing something, but why not just skip it?

Guess it depends on the DAC. Recently bought a Headroom Total Bithead simply because it sounded like a cool idea. It's an outboard DAC / Headphone amp designed to run off of a computer USB port. It's totally plug and play -- plug it in and it configures itself to run as the default sound card as long as it's plugged in -- thus bypassing the onboard card. I'd previously been using the DAC on my card (which is a decent soundcard) and then running analog into an outboard headphone amp (an older Headroom), but the sound was pretty mediocre. Running USB direct to the Bithead is a lot better -- hardly perfect, but definitely a huge improvement. Perhaps not what you're looking for, but the concept (bypassing the onboard card alltoghether) sounds like the way to go to me....
You need to bypass the Kmixer in a windows based OS. Kmixer upsamples to 48khz, this is a no-no. It does not matter that you use onboard sound or any other device as long as the output is bit perfect. Hence the $10.00 dollar Cmedia solution will output a 44.1khz bit perfect signal to the DAC.

This has been researched extensively by others and myself. I am runing Foobar2K with bit perfect output to my Music Fidelity Tri-Vista 21 DAC. Hope thhis explains it clearly and to the point.
Thanks for the great responses.

Racerxnet: That sounds like the way to go. I use Cinemar MainLobby, which is a front end for J. River MediaCenter. I believe J. River has something like bit perfect output (it has bit perfect ripping).

What kind of connection do you use to the DAC?