Version 1 of my DIY digital music server was the cheapest by far ($0) but unfortunately was lacking in the sound quality department.
I had my amplifier (A&R A60 circa 1989) and desktop PC sitting in my office while my speakers (Linn Index II circa 1990) were in the family room. All I had to do was connect the PC to the amplifier and use the PC as a source. The PC was certainly no high-end machine but it did have built in sound provided by the mother board. There was a line-out jack that I could connect to a line-in on the amplifier. I already had a 1/8 jack to RCA cable (actually this was a little more complicated as the A&R A60 used DIN connectors, I had to also use a RCA to DIN adapter too) so I hooked the two together and tried playing a 128 bitrate MP3 via WMP. The sound was Ok but it certainly left quite alot to be desired.
After researching other people's experience with doing something similar it appeared that using a built-in sound card (or even a separate sound card) was not going to give the sort of results I wanted. I was going to have to look at other alternatives to hooking up the PC to the amplifier.