Its just easier to blame someone else. You can try an ugly solution which is to put a piece of black electrical tape with a pin hole in it on top of the IR receiver. Place your emitter over this. This cuts down on the signal reaching the receiver which may help. Also, some emitters have a high power and a low power side. Simply flipping the emitter over (sticky side out) may help. Otherwise, you can try a 680-ohm 1/2 watt resister in series with the emitters positive lead. This will also reduce power output. This assumes of course that your pioneer is being overpowered.

Some pioneer stuff operated at a really high frequency which was tough for some eyes to pass. I would suggest looking at Xantech.com or Russound.com and browsing their tech bulletins for information and hints.