I'm not surprised that the 100 watt sounds dull with the presence at only 6-6.5. I put it way up to 8-9. Mic'd tones always sound much better to me with a lot of presence. Then again, the Mesa cab has a pretty smooth topend that allows more presence without getting too fizzy... How is the clean channel on the 50? Can you get it to stay crystal clean with a lot of volume?