So i've got a car amplifier, named PRS-D4200F, based on ICEpower technology...
I haven't liked it too much, so i decided to mod it somehow.

So, schematics, plans, etc... 
Looky looky! It's input stage is on the average side, xover is horrible, everything is overcomplicated...
And then if i want (and i want!) to use it in bridged mode for hefty 300W per channel into 4ohm, then you just have to have everything matched well, otherwise it's a bad idea to bridge it...

Long story short, schew all the input stage, xover and buffers, throw this PCB just before the ICEpower stage kicks in and... it should be damn good.

So, whtat's on the board?
 - Rather simple PS section, followed by R-C filter (a good start!).
 - Nice opamps on the input - AD823, FET-input to cope with RF crud, and be linear with high-Z sources (volume attenuators e.t.c.).
 - Fully differential amplifier to convert SE to balanced - wide BW, quite powerful output stage and... it is absolutly symmetrical, which is damn sweet! It's a tought one to get such symmetry with regulat opamps, so integrated solutions win.

Shematics V0