GK amps have a slightly similar upper midrange voicing. I havent been able to try the GK Fusion amps myself, but imagine they might get into that territory.
But honestly, compared to most other amps out there these days the Bass 400+ has a pretty unconventional EQ and input/preamp setup.
The bass and treble are flat at 3 and will be boosting too much past 8 to be useable (when you go past 7 with bass or treble it "steals" gain from the other EQ bands).
And the mid is cut only. The graphic EQ is post preamp, basically it is the power amp's eq, and it is solidstate (booooo) but it is inductor not gyrator based (yaaaay!).
And the preamp inputs are not just a passive/active input. The one lower gain input is very Bassman-ish, at least as much as a Mesa can be. The second input is higher gain and more mid-forward. I've been told it is based on a Showman.
I can get a lot of amps to sound Mesa-ish at clean levels.
But only the Bass 400/400+ overdrives like they do. That dry grindy overdrive with tons of low end.