Finally took some decisions.
Project will use a cheap mini tv as display:
The next step I took was to plug everything to a simple power outlet, since every part I'm using is either 5v or 12v an ATX power supply sounded good, also I had a power connector adapter laying around, used it to make this cable with all the required voltages plugged, tried to avoid modding the PSU to get some maintenance possibilities:
I also ditched rune audio in favour of raspbian with mopidy. Mopidy has a HTTP API and some awesome plugins, will try to make my own web front end to run it on the display using Fluxbox Window Manager. I have also worked a little more on the code for controlling the volume and the playback, will try to turn it into a mini keyboard for navigation inside the web client. All it's written in nodejs and mopidy has a JS wrapper for it's API.
All things are wired to ATX and inside of that green box until I get something nice to put them into.
A reused and old usb hub now wired to ATX.