Anthony Padilla just sent me a fully modded/rebuilt TacT S2150 amp. Here are some of the changes from stock:
Install high voltage/current toroidal transformer for DSP board
Replacement ofl five pulse transformers with Scientific Conversion SC947-02
Power entry module wtih built-in noise "firewall" and Furutech IEC
Replacement of all caps with Sanyo Oscon
Replacement of 3.3v regulator
Replacement of rectifiers with ultra high speed, soft recovery diode bridges
Replacement of all cables with Cu-Ag teflon dielectric ribbons
Addition of EMI/RF sponge material and magnet wires
Replacement of Mosfets

I haven't had much time to listen yet but the improvements over stock are quite impressive. Much more to follow...
Next week I should have a fully modded 2.2X as well. Experiments with DSP tri-amping and bypassing the 2.2X on the mid/tweeter section (i.e. using it only for the subs and main channel woofers) are planned too
