I feel a bit ridiculous posting about this under the circumstances, but I promised some folks initial thoughts, so here goes...
The "problem" is, it turned out the place we played last night was really tiny, so this rig was like bringing a sledge hammer to drive some finishing nails into some trim board. I had the gain set to about noon, because I generally believe in setting any preamp with tubes in it such that the tube sees a pretty strong signal. Unfortunately, this meant I could barely turn the master up at all. Seriously, I had it down around 8:00 or so all night.
For reference, here's the rig, tho not the basses. I used my Skjold and MTD for last nights gig. That's a Series 2 UL410, btw, in case it's not obvious enough in the pic... kinda' hard to see.
I settled on using the flat profile, and even ended up pulling a bit of the bass out. The tone was very clear, quick, big, full, and puchy as all heck. I really wish I coulda' opened this thing up some more, and really get into it's "zone", but I had no desire to make people bleed from the ears, so I resisted the urge.
I'm impressed with this amp's clarity and responsiveness... I've always liked Mesa's direction for a "big" sound that has a lot of "tubey goodness" in it... IMHO, in pretty much all their bass amps... regardless of how many tubes are involved. However, most of their amps don't quite have the edge I like, which is why I've generally been a SS kinda' guy. This amp changes the rules for me. I've always liked some characteristics of a tube tone, but in most cases, not the dynamic response to my particular playing style. Well, I really need to spend a bit more time with this amp and push it if I'm granted the opportunity, but this amp might very well be "having my cake and eating it too". So far, VERY cool.