Okay so here is my Idea....(not sure how I am going to pull it off but I want to) I have two Avatar 2x12 cabs that are 8 ohm. I want to add another two 2x10 Avatars to the mix both 8 ohm. Now I had planned on building my own head with a nice 2 channel power amp that will handle a 4 ohm load per channel. But I am not sure how this will work with the preamp selected. I want to use the Tech21 SansAmp Rackmount. Sound like a good idea? I would like to have a stack on either side of stage to help moniter for my guitar players. Mainly just a curiosity. Never ventured in on more than just two cabs.