You could get a transit ($55-80) for 24/96 or HagUSB ($70) for 16/48 resolution to convert to Toslink or Coaxial from USB and use Coaxial for free or the $18 TPA toslink module. HagUSB, you can buy the kit to save money and install it internally as a receiver module as well. The transit is roughly the same price or lower as the TPA USB module and does higher resolution (may not be as good as a receiver though), so its up to you. The TPA USB module can output straight i2s on the other hand and will save about $10-30 after you calculate cost of extra connectors or modules involved. Toslink or coaxial seems very important to me if you even want to move away from a purely computer based system in the future and the 24/192 receiver chips for the modules are now OOP, coaxial input is free and Toslink is only $20. I probably wouldn't bother with USB at all if I had a desktop based system, I'd just get a sound card with spdif or i2s out. Not using USB as a transport would give you the option to use many more DACs with your computer setup as well.
Soon (by June) I should be able to find out which option I prefer between the transit or TPA USB module.