Wow, thanks for all the replies (I didn't suspect this much!)
I'll give things a try and see what will happen. As far as I've found out on Usenet, searching for "ATTAX 100 MIDI" (my guitar amp), I learned that indeed there is not much to control via the MIDI-output on the amp, apart from switching between the 3 different channels on the amp itself.
About quality of sound: I wasn't planning to make professional music, just making some nice sounds for fun and maybe for friends to listen. Plus, I like the somewhat "lo-fi" sound you get with 8-bit audio (I still play a lot of Mod-files every now and then on my PC).
Maybe I'll put up some soundfiles on a server when I succesfully have recorded some, but that could take months.
Does anyone know if it's possible to play the combined Amiga+guitar sound through my amp's speaker, or does the sound go through the Amiga sound output?
Cheers,
McVenco