Raspberry Pi based servers work best with Async USB DACs, the Pi internals suffer from rather high jitter on 44100 audio
As a network server?
TBH I've compared it to my aging Qnap NAS and it sounds a little better to my ears but that maybe a distro difference (if you believe in such things).
I also compared it to the powered WD 2TB HDD directly to PC and again it sounded a little better.
So maybe yes hooked directly to a DAC things are not quite so good (but plenty seem to like them that way)
But I've been pretty impressed by the PI running light weight Minimserver using Bubble DS next as a CP to my streamer (Jplay).
Dave how to go about it is pretty easy.
download this
https://www.raspberrypi.org/downloads/raspbian/
and follow the installation guide.
Then follow the instructions here
http://minimserver.com/install-raspbian.html
Raspbian Jessie has Java pre installed so no need to worry on that.
command lines are easy enough.
The first instruction line ''cd /home/pi'' does not work for me but substitute it for 'pwd' and then cut and past the rest in.
I Have Nil Linux experience but it took about 1 hour to have a working server up and running.
and the price?
Crazy cheap.
I think that my server came in at around the £150 mark.
Or if you have an old PC/MAC lying around (no great processing power needed) then install Minimserver on that.
To run either headless install Minimwatch on any network connected PC/MAC and control Minimserver remotely.
Then if you like, run something like Bubble DS NEXT on an Android table/phone to remote control.
It's all pretty cool IMHO and sounds more complex that it actually is.
Hook it up to a network and good to go.
drop me a PM if you'd like a little ''practical help'' to get things running PI wise.
BTW all of the software and Raspbian is free to download so nothing to lose cash wise on that.
I've also use a PI as a renderer running Moode Audio player.
http://moodeaudio.org/images/moode-twitter-header-v2.png
With decent sounding results into my Buffalo3/legato/wave io.
Pretty impressive considering he low cost.
I've also tried Moode as a music player with just a DAC and Powered HDD connected with decent results.
IMHO Moode as a renderer or player whilst not the ultimate in quality sets a pretty good standard which would be hard to beat at twice the price in commercial land.