Linux - Ubuntu 15.1 - Roon on an AMD A4, passively cooled
RPi 2 - PiCore - HDMI out
Pioneer receiver - HDMI in - Airplay
Apple TV 3 - Airplay
Quadral speakers

Other place:
Vortexbox on old single core
Kaneda pre-amp
Hiraga Class A amp
Squeezebox 2
Dynaudio Axis-5 / Spendor BC-1 speakers