I recently built and have been upgrading my music server. It is all from eBay and Microcenter which the later was been quite nice for the advice. I'm here to let you all know that you do not need to use server 2012 or the top-of-the-line equipment to have a fantastic sounding music server. I'm not saying that to be argumentative at all. I just want people to know that on a budget you can build something that you and your friends will really really like to listen to. So don't put it off because you think you need to spend hundreds on Server 2012 and mega buck parts.
The highlights of mine are:
Asrock h61m DGS Mother Board.
Core i3
8gb PNY RAM (cheap).

Replaced processor fan: Cool master T4 without fan. Silent.
No chassis fan till summer then maybe a <20db fan.
Paul Pang USB v2 card (must have).
Acopian linear power supply from eBay. 5v 1 amp powers the Paul Pang USB card.
Bag of mixed connectors from Microcenter to make custom pigtails.
Windows 7 home premium
Toshiba 128gb SSD
Jriver and Jremote on my iPhone to run from my seating position.
Random old mouse, keyboard and monitor.
Cut off power cord for Acopian.
Cheap case from Microcenter.
Old power supply from e-machine.
Toshiba 1TB USB 3.0 drive.
Next up is a 5v lithium polymer battery for the SSD. I have looked at 3 models at Microcenter for about $29. You will need to mod a connector and a USB cord with thicker wire as the power cord.
That is it for now. Sounds so good I cannot believe it most of the time. One warning the motherboard is usb2.0 so you might want to go to a model that accepts USB3.0 on the board, not with a adapter on the express slot.