I use one of the eq effects, and set right it can be pretty transparent. I have an m5-pre, and an m9-in loop. When I need a clean boost, I use the m9, and the eq as mentioned (try them all see which works best for your setup). When I need something a little dirtier, I use the m5, to push the amp... with either a boosted eq or the screamer with low gain. That's me.