Wish I bought a U24 when it was still available :(
The U24 is a great device. Keep an eye out on Ebay or in some of the headfi forums. The U24 will change your way of thinking in terms of your original post. I got mine on Ebay for $40 and am certainly satisfied enough in keeping this in my system until the technology matures. There are other devices, however I like the array of available input/outputs and it's ability to be utilized for other applications.
Just the analog outs straight into my preamp blew me away initially and forced me to be more serious with the "PC as a transport" gimmick. Since then I've been able to aquire an EAD DSP-7000 MkII, Museatex Melior and Cal Alpha DACs to audition utilizing the U24 strictly as a 44.1 khz pass-through device (lossless files fed through Foobar/ASIO.dll). I must say that a good DAC will remove any hint of digital glare that the U24 may be conveying. I found the Museatex to be extremely detailed, the Cal Alpha to be the most analog sounding and the EAD to sound almost as if it were a hybrid of the other two DACS. Still trying to decide...
Bottom line, I believe that in terms of strictly Redbook you can't go wrong with the U24 and a bargain priced older DAC. I think that since jitter reduction is inherent to the "PC as a transport" option, then perhaps these older DACs can do a better job of just being a DAC. I think you'll be changing your view in very short order, and for little investment be enjoying music in an exciting new way. Have fun.