i used to own one...that preamp is insane....ever sinced iv had it, i swore my next amp homemade,modded, whatever, needed a sweepable and assignable mids section..
when you dialed in the mid frequency...thats what opened her up...went from a Marshall fire and sizzle to a dark robustly low end recto tone....sold it to GC when i worked there..still there too. should go give them $100 and get it back.
I personally didn't dig mine much when I had it. Basically I was able to dial in one great tone but, I could do that with any amp, don't need a midi preamp for that. YMMV Psychodave really does like his and he's got a good ear for tone and is a great player as well.
I have one that I keep as back up in case my Triaxis ever goes down. Very good pre-amp. Plenty of good tones in there. The eq is very good, the noise supression is a nice plus. Get it.