I also think yanking the hotplate, or at least dialing it back, would help along with mucking with amp placement. If you haven't already, try getting it off the floor, not backed against a wall (too much), and get it pointed at your head. :) Then work those EQs!
Changing your setting (e.g. bedroom to practice room to yet a different practice room to venue, etc.) always makes things sound different (and so, perhaps -- subjectively, at least -- worse). I would think the amp can cut it, you've just got to mess with it to get it sounding as good as you can in different spaces (since, after all, when you plunk it on stage for that first soundcheck, it will a) sound different again, and b) what you hear on stage won't be what the audience hears anyway, so you have to close your eyes and trust the soundman, which is not always justified but, eh, what choice have you got? ;)).
This is a lot of the reason the darn things have twiddly knobs and dials, after all (I assume). Otherwise they could just built an amp with "The Tone" and no settings. :)
