how about trying a stereo guitar proccessor through the effects loop of both. L/R in and outs to to the send and returns of one amp being the left and one ampp being the right. of course you could only use the effects out of your proccessor throught the effects loops, and you'd have to use both amps pre-amp for channel switching which could be tricky, bit if you had the right switch that could control channell switching from clean to distorted to lead channel it would sound really good and wide. The only bad part is, youd be tap dancing all night getting the channel you want. I've done it and it sounds sweet, but found out it wasnt worth it for me. I agree with MIXMKR, that it doesnt translate to the front of house as much as you hear it on stage.