Allright so here's the deal:

I got an old B&O reciever with one chanel blown that i changed into a guitar amp, using the phono in works fine for my crappy home made pickups, but whenever someone with a real guitar comes by they only have one option: heavy distortion, since their output is way bigger then mine. 

So I was thinking that i wanted to put a pot on the wire leading into the phono in so i can get clean sounds when i want to....

Now, i don't know jack about what the things pots say mean, i built some effects, but only by following schematics and doing what i'm told, so in this case i'm lost.

What kind of pot should i get? how many K's and what type?

thanks in advance!