Quality digital sound from a computer is the easy part: Making it un-frustrating and non-distracting is another matter.
FWIW, I just bought an Fiio X3 Mk II music player, and it seems that some of these Fiio devices can also serve as USB DAC, so you can think of them as multipurpose audio gadgets, offering SPDIF, line-out and headphone-out - or you can simply use as a portable music player. Headphone amp has enough moxie for my Fostex orthodynamic headphones. The sound? Wonderful as you'd expect of any well-engineered product these days. NWAVGUY's old blog contained bench test results of an Fiio product:http://nwavguy.blogspot.com/2011/03/fiio-e5-headphone-amp.html
I gotta laugh at my music PC projects over the years: My earliest was total overkill and ended up costing far more than expected. Current Raspberry Pi setup and Fiio player would both fit inside a shoebox, with room left over for the shoes! Neither had any real impact on my finances.