yah, you cannot select which output will be sub, and which will be front, etc......the pioneer decks wiil either have 1,2, or 3 outputs. with 3 outputs, you can have ft.r.and sub separation. with 4 outs, you have to chose whether you want the rear to be sub (which locks it as a non-fade output) or normal rear. the odjustment on the front rca's is full, or (can't remember what it is called.....hfp effect, or something) where you set the frequency to cut the lows out of the front speakers. the other cross-over on there, lpf, is to set the frequency, phase, and level of the sub. if you select none/off, then the rear/sub rca's will convert back to full range rear chanel that can fade..... i hope this helps. so, i'm still not clear....... what adjustments are on the sub amp? just gain? or is there a switch? check also the bottom pannel, it could be hiding in the middle of the circuit board, through an access slot. if there is a swtich there, it may also be configuration switch, and i've only ever seen what it does printed on a faded sticker, or in the manual...