buy a mesa TRADITIONAL. i was using the exact same setup as you but with a tube screamer in front of my head, to cut some of the bass. i also know exactly what your talking about with the brittleness. i mean the marshall still works with it, and its all preference, but i just a traditional cab last week cuz i was so sick of the sound i was getting. the trditioanl is LOUDER, handles alot more bass, is a lot thicker, more clarity, less high end, overall a lot more quality sounding. that is how i feel at least. the other dude in my band uses a 1960A still and we've done tons of comparisons all day long with the same settings but with the 2 different cabs. i would take the traditional all day long. i tried out a standard at the guitar center with the same setup and yes the bass is quite floppy and muddy.