Turning a Yamaha RA-100 combo into a head amp

[Katja]

Hello! I'm new to the forum and this is my first post. I'm 27 years old and decided my new hobby is going to be building solid-state amplifiers. 
I already got a project I'm working on, but I have no idea where to start. Recently, the rotating speakers of my cherished Yamaha RA-100 broke down. I use a very heavy fuzz on guitar, so I loved this amp because it is very clean. In any case, my Big Muff worked really well on it, it had a very smooth fuzzy sound which was amazing. The rest of the amp was pretty much hunky-dory, and since you can't really find replacement rotating speakers anywhere and I didn't really feel like dragging this gigantic amp around for gigs anyway, I decided I wanted to turn the combo into a head amp. How hard could it be?
Well, as someone who is a complete novice to electronics, pretty hard. So after a long search on the webs, I actually manage to find all the schematics for the Yamaha RA-100. But I still haven't got a single clue on where to start. I'm not sure which parts I can leave out, because they're parts of the rotating speakers circuitry and I don't know what parts I need to get it running. So I dismantled the whole thing and it's pretty much collecting dust right now.
Could anybody help me out please?

[galaxiex]

Here's a guy that modified one of these...

http://www.lydian.ca/yamaha-ra-100-rotating-speaker-organ-amp/

[Katja]

Wow amazing! Thanks, I'll have a look at that.