If you will only be doing computer audio, then I urge you to research USB DACs. There has been a lot of development recently, and USB now handles high resolution files. There are two approaches, asynchronous (e.g.,Ayre, Wavelength, HRT, Wyred 4 sound) and high resolution synchronous (CEntrance, Benchmark). Within your budget, I recommend you'd look at HRT Music Streamer II+ (the II+ will have much better analog output stage and components than the II) or the II Pro if you have XLR inputs on your preamp. The CEentrance products should also warrant your consideration.
Is the high resolution USB as good as the digital coax? Depends on a lot of variables. How are you getting coax out of your computer? Musical Fidelity V-link or M2Tech hiFace Asynchronous USB To S/PDIF Converters? Or just a basic computer soundcard?
I am assuming the latter. Why don't you borrow the Musical Fidelity combo from your other system, and hook the V-DAC up both via coax and through the V-Link, and listen which connection sounds better. That should give you an idea what direction you should go, coax or USB
Is the high resolution USB as good as the digital coax? Depends on a lot of variables. How are you getting coax out of your computer? Musical Fidelity V-link or M2Tech hiFace Asynchronous USB To S/PDIF Converters? Or just a basic computer soundcard?
I am assuming the latter. Why don't you borrow the Musical Fidelity combo from your other system, and hook the V-DAC up both via coax and through the V-Link, and listen which connection sounds better. That should give you an idea what direction you should go, coax or USB