I wonder if you might have any pointers kind Sir? I'm currently working on my Pioneer A400 and I notice you have mentioned in previous threads that you have “modded” a few of these in the past. The story begins when I noticed my A400 wasn't sounding quite as good as it used to, I decided it was time to replace some capacitors. I have replaced capacitors in various HiFi and Av equipment in the past. The sound was still punchy and dynamic but a little rough at the top end. First of all I replaced the old Elna 10000uF 50V smoothing caps with Nichicon Gold series ones of the same value. Then I replaced the 2.2uf 50v coupling caps, again with Nichicon gold series, off the top of my head I think their location is c201 and c202 on the schematics. (I wrote to Tom Evans and the Nichicon caps were his recommendation) I've also re biased the amp, I've adjusted to voltage at the biasing pots with a meter at both the large white 330k resistors to 60mv. Can this be increasd further? However, there is something missing, The amp has lost it's dynamic slam and the Bass is a little light,it's sounding as if as though something is holding it back and a little flat, however it now has a fluid, smooth mid to top end. Any ideas what else I can do to improve matters in the low end of this amp, I am I going to have to replace all the caps or is there something else I should do? Thanks. Tesler