I modded the crap out of my Digital MPA - I'm sort of happy with it. I socketed all the opamps (pretty much a waste of time - the key ones were already socketed and I screwed up the multilayer board pretty bad). Here are some things to try:
Put OPA 2134 opamps in it somewhere. I don't know the schematic of that one, and I don't remember the schematic of mine, but I think there were really only two places that did much (and both were socketed). The sound was "slower" - that is, slower to react to transients, and smoother, which was nice to me. Sort of a "smokier" sound, if that makes sense.
If you're having troubles with clipping or harshness (which, on my unit, I'm guessing, was caused by the 12AX7s pushing too much juice down-circuit and hammering some other components that weren't really spec'ed right), try swapping the tubes for a lower gain cousin - 12AY7 is probably the best choice, but I always had a hard time finding those. 12AT7 can be nice, but a lot of them are noisy. 12AU7s can be perfect, but they are a lot lower gain. Remember - if you're using a computer in your chain somewhere (and I assume you are), you don't *really* need
a high gain preamp. You can add digital gain later, and also for monitoring if you're set up right.
