Are most DAC's compatible w computers?

The short answer is "yes". If your soundcard has an S/PDIF output then you should be able to hook it up to any DAC with an S/PDIF input and it should work. Sean's points about reclocking are to the point as well. You are using your hard drive as a transport when you use your computer. If the clocking is off when it sends the signal out, and it is not compensated for in the DAC or in some kind of jitter device in between, the effect on the music can be profound. Though it may sound OK (like actual music coming out of your speakers) the potential loss will be in the PRAT aspect of the music. You may find that your foot just ain't tappin' anymore!

Either get a DAC with superb clocking, or, perhaps one of the pro-DAC's with USB option like the Apogee DAC. Rumor is that Benchmark is working on that option as well. USB is a bi-directional interface which allows clocking information to move both ways. In some cases, as I understand it, this can be of tremendous benefit in eliminating jitter. I'm not sure if this is the case with S/PDIF. If you went with a USB DAC you would be bypassing your sound card altogether.

I've been experimenting with the same technology having ripped all my CD's to a 250 gig HD. I'm currently running my laptop to an ESI Waveterminal U24 USB device, digital out via S/PDIF to my Muse Model 2+ DAC. Results are superb. I do believe the Muse does have excellent clocking. I've never tried the DAC in the Waveterminal (it does have that option), but don't imagine it's going to compare well with the Muse. I'm not sure if the Waveterminal does any jitter attenuation at all via the digital throughput - does anyone know?

Marco

BTW while much is made of the two way nature of USB,
I can't find anything in the technical descriptions that supports the theory
that USB does anything about jitter - the two way function is its device
communication and control protocol - take a look at wikipedia.com

Quite correct, USB does absolutely nothing about jitter in and of itself. It
must be the device that is connected via USB that is built do take advantage
of the bi-directional nature of USB that would do something about it. Take a
look at the information provided by Gordon Rankin over at Wavelength on the
subject here

To get good sound out of a pc will cost a bundle. You need quality
software for burning, more internal dampening, huge hard drives and.....I
tried to bypass the sound card with a usb run dac and was totally
disappointed with the quality.

I don't agree, and am quite curious why you couldn't get satisfactory sound
from your setup. Which USB DAC did you try Elevick? As far as the cost; Most
of us already have a capable PC or we wouldn't be posting here. It does not
take an extremely fast PC to stream music, nor does it require a whole bunch
of RAM. A Waveterminal is currently around $159 and will connect any USB
equipped PC to any DAC with either S/PDIF or Toslink inputs. The only other
investment would be in an external drive to store the larger files (a 250GB
Lacie drive is about $219) and most folk's entire collections would fit on that
single drive in Apple Lossless. Total investment is about $400. In
comparison to what folks on this site spend on front ends I'd say that is a
mighty small sum. Even if you add $1000 for the computer itself you are still
at the price of a nice front-end CD player or entry level turntable rig. Oh,
and iTunes is absolutely free and is excellent software for ripping and playing
your collection. Using this system through my Muse DAC the sound is
nothing short of superb, and I find no advantage to running playing a CD
through the same DAC - I am quite sure that an A/B/A comparison would
leave anyone stumped. I'd challenge anyone here to consistently identify one
from the other. As has already been said, the tremendous convenience of
having your entire music collection at your fingertips is priceless!

Ckorody - Thanks for your point of view. Don't get me wrong, I was certainly not recommending (or discouraging) that anyone go out and spend $14K on a USB DAC. I'm not sure where you are getting that price. The two USB DAC's Wavelength offers are the Cosecant at $3500, and the Brick at $1750. Both are tube-buffered USB DACs. The only reason I pointed to the site was for the explanation of the two-way nature of the USB interface. I've never heard any of their products. Should you care to take your puzzlement directly to the source I believe Gordon Rankin is a frequent contributor over at AudioAsylum you could publicly ask him yourself there, or, of course, send him an email. It does make sense to me (obviously)...if there the information is going just one way there is no reference point to the accuracy of delivery from the origin. If two way the device has the potential to check the accuracy of the origin and adjust (buffer) accordingly. It sure seems logical to me. I completely agree that you do not need to spend a ton of money on this technology to get very rewarding results. Thanks for the links too!

Another note as an addendum to your post: The Waveterminal does utilize an internal clocking device. The feed from computer to Waveterminal is indeed USB. From there you can go via either SPDIF or Toslink to your DAC. I've done no comparisons to a USB DAC, but compared to my Muse transport hooked up to the Muse DAC via their proprietary connector (optimal for those two units). FWIW I cannot tell the difference between a CD on the transport and the signal delivered from the hard drive via the Waveterminal (either in Apple Lossless or WAV), at least in the system as it is hooked up in my home right now (currently at somewhat of a compramise in room treatment). I'll be curious to do the same test in my main system, which is currently not set up due to a renovation.

Marco