For me, MarkBass was another 'new' amp line that was getting a lot of buzz, just like in their day did SWR or Trace Eliott, etc. I gotta admit the color scheme was a little much for me, but what the hey, that's just me.
When they got to where they had Sig amps from Jeff Berlin and Alain Caron, I thought, 'time to check this out'. I did, and was disappointed. The 15 in the JB just sounded average, when by now, a single 15 bin should be a relatively achievable target. But I was really disappointed in the Caron amp. I'm a huge fan, I understood the reasoning behind the amp, but it too just sounded average, and in either case, I could not approach a tone I wanted.
Now this is all hugely subjective, but for me and what I wanted to hear, it just wasn't there.
Where it's made doesn't really matter, and I think to a point, guys may think that since they are SO in bed with Guitar Center, it must be lacking somehow. And yet, Sterling Ball (as smart a guy as there is in MI) uses them to re-issue the classic Music Man amps, so there must be something there. But ultimately, it just wasn't for me.