Here is a little project of mine: a 4 zones multiroom player in a single box.
4 Amp+, 4 Pie model 2, a switch, a power supply, all pacckaged in a single tight aluminium case, with single network plug, and banana plugs on the back.
Software: raspbian jessy and squeezelite (https://github.com/ralph-irving/squeezelite). Server is on Synology NAS.