I push my R40 all the time. I set master at 12 o'clock and adjust gain from there. Mostly run Bass at 11 to 12, Mids 11 and Treble around 2 o'clock. My Smith has excellent onboard effects so I fine tune from there. I did change the 10inch speaker out to a Seismic aluminum framed Richter, 3" voice coil @ 200 watts. Sometimes I run the Contour and Bright cause I like it snappy and clean and I have never had to use the overdrive. Used it at Diamond Jim's and the bass player for the house band uses an Ampeg 8x8 cab. He couldn't believe the sound I was getting from that R40. That little amp is all I need but I feel that Fender should have put a better quality speaker in their Rumbles....just my opinion.

