Hi

I had the same problem. You have 2 options:
1) buy a Pioneer CD changer to AUX converter (about 90 Euro) and connect the Riocar outs to the Pioneer, blocking the Riocar volume at 0 dB. The sound will come from the Pioneer's amplifier, and you'll loose the nice Rio parametric equalizer since Pioneer own Eq. will do that work. So Riocar will sound not as well as it could.

2) Buy a good 4 channel amplifier and pug it directly to your Rio, ande let it to equalize your music, plugging your Pioneer to his AUX inputs. You'll have to find a good volume on your Pioneer not to distort, and its eq. curve to 0, quite difficult due to Pioneer default powerfull equalizing.

I took the option 2, but now i have another problem: my Pioneer IR remote works on 2 units at the same time, so i have to fix some black tape on the IR sensor on Pioneer. Now i have to push buttons on Pioneer to change the FM station...

It has a bad solution, i guess. The best sound you'll get will always be through Riocar, and you'll have visuals with AUX inputs.

Cheers

mpelaz
Madrid