I'm running an M4 with a mesa 20/20 through an H&K red box classic direct to house for live applications. At home I run it into a rebel 112x. Of course I only use 1 of the 2 channels on the mesa and alternate them. It would be nice to run stereo and use both channels but I have not tried it yet. I keep the mesa's presence maxed and volume at 12 o'clock. I get all the volume I could possibly want in a live setting. I cannot imagine needing more power! In case it helps, I play with a 7 piece band and use IEM's. I love love love the mesa...bought it used on ebay for $599 in September.