I used to run an Alesis 3630 dual comp. My SWR has one built into it, but I never run it. Never had the need to. I'm with Dave and Joey here, I have a huge amount of dynamic control in right hand and compression can alter this. I don't discourage using one but compression is just not for me. But now for guitar I love compression, especially when there is a need for an overdriven hard but smooth sound.