Billy Gibbons sounds great, he uses 7's!
Highly doubtful Mark was playing straight into the desk. I've had a few MusicMan amps including an HD130, they're quite "unforgiving." Almost Hi-Fi sounding (solid state preamps) compared to your typical Fender. Also, they don't have a direct out.
He probably needed more onstage volume, and used whatever loud/clean amps were available at the time.