What kind of sound are you going for in your rig?
It sounds to me like maybe getting a Triaxis in place of the mark IV would be the way to go. I can't tell you how versitile the triaxis is.
You'd easily be able to make enough from t he mark series to pay for the tri, ad then you filpped the quad, you'd pay for a nice power amp, like the Mesa 50/50.
You'd slim down the rig considerably, and on top of that, if you got a version 2.0 triaxis (most common) you end with every parameter that is midia assignable and contraollable via
expression pedals. Mesa has a great tutorial section in their manual that demonstrates how to set a patch that goes from a
clean tone to an amped up chunk with the sweep of the pedal.
Anyway, that is just my opinion, and just a drop in the bucket.
Every time I start to get bored with my tone, I poke around, reconsult the manual and look for cool sample patches that truly demonstrate the flexibility of this preamp. I'm never disappointed. If you are atweaking/ experimenting person, you'll LOVE the Triaxis, I can almost guarantee it.
Bamm