First post here:
I just want to say I have a modified Mesa Boogie Triaxis for bass guitar. In fact, I used it on my band's first two albums (Abigail's Ghost)
To be honest, I was never quite sure what the actual mods were, but I had gotten in touch with a guy at Mesa through another Bass Triaxis owner in the New Orleans area, by the name of Ben Strange. At the time he was working at Guitar Center and I just so happened to chat him up about how much of a fanboy of Mesa Boogie I was at the time. (Full disclosure: I own a Basis M-2000, Mesa Mark IIC+, Mark IV, Triaxis, and several cabinets) I then bought a stock Triaxis and immediately sent it off to Mesa for modification via my contact.
A little bit about the sound of the unit:
It's not a traditional "bass" sounding preamp, but it has a very thick, gooey gain that I use in tandem with a clean amp and another distorted Marshall DBS/custom Human Gear Animato combo. I use the red channel with the mids cranked up.
I've been recently going back and forth about selling it and buying a Mesa distortion pedal with another amp to fill in that space. I feel like with my current setup the Triaxis is kind of going to waste being on one setting, but it really sounds great for what it does, and quite unique. I'm sure there are some Triaxis/Mesa aficionados who would be interested in it as a curiosity piece.
Regards,
KW