Hey, I just got a Mini CMD 121P from Guitar Center today.
I actually talked with a fellow bass player last night about MarkBass gear. He said that he tested it out and didn't like the sound, too clean and thin, he said. Now, he's an Ampeg SVT-3 user. I think I know what's going on. For anyone where they use the amp as part of their sound, the MarkBass is not it. However, for anyone who wants to use the bass guitar and let its nuances shine through, this is the amp to check out.
For me, if I need the tube compression sound, I could use external pedals, Sansamp et rest. However, to find an amp that really lets the bass guitar's sound shine through, those are rare. MarkBass is really it. In my case, now I really know how an Ibanez ATK really sounds, with no colorization of the amp. If you ever test out bass guitars at a GC store, use a MarkBass as the reference amp. You could clearly hear how the pickups work, how noisy some are (!) and so on...
Otherwise, I have not yet played this amp in a gig environment, playing back home in my studio, volume level just below 1 was already loud enough. With a possible 2x10 cabinet for some cases where a PA is not around, that's all I need. Imagine taking this amp into my Mazda 3 and going from gig to gig. For me, big/heavy amps and huge cabinets is really the dinosaurs of the bass age now. --Kent