I used a pi 4 in a touchscreen case, so I just strapped it to the top of the amp. I used an aux cable to plug into a cheap audio receiver which I replaced the amp interface with.

Looks ghetto as hell but it functions perfectly lol. It has an extension cord running out the back as the main power cord.

That's really cool!

I did a similar project using and old guitar amp and a raspberry pi with a touchscreen!