A while ago I got an Alesis MultiMix 4 from eBay which I assumed was not working (I was looking for broken things I could attempt repairing), when it arrived it seemed to be working perfectly so then had to find an actual use for it.
This is what I came up with, it is a bit basic for what this mixer is actually capable of but was something to do in the time I would have spent trying to get it working if it was actually faulty.
This is a simple enclosure for two 40W amplifiers and a Raspberry Pi, the audio input and output from each is broken out to 1/4” mono connectors on the back of the enclosure for connection to the mixer which sits on top of it in holes that line up with its rubber feet.
The idea is that the Raspberry Pi would be used to play music using software such as Squeezelite while still allowing the speakers to be used for PC audio through the USB connection on the mixer.
The CAD files for the enclosure can be found here.