ok, I've seen loads of guitarists do this, basically they'd have a Mesa for Gain and A vox for cleans. How would I go about doing this. I have a marshall and a Hughs and kettner, i want the marshall for cleans and H & K for distortion.
Do both amps have a Line Out? I think that has something to do with it. It would help if you posted specific models of each amp.
High as tits
Get an a/b/ab box it is a box where you plug your guitar into and then from the box there are two different outputs that are footswitchable and you can choose one, the other, or both. They are cheap and easy
Or just slave the amps.......... via an extra input jack on the main amp, preferably the one u use for the dirty tones/
Tone is all ...... well probably 75%, in your fingers.
The rest depends on your wallet's thickness !!

Keep the faith, baby!!
dude all you need is a line selector. its simple as that. you run a cord from the guitar to the input in the line selector and then 2 cords from the line selector to the appropriate amp.