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.