Audio Systems: Using headunit speaker outs as well as amp, infinity kappa, rca outputs

Question
My Car audio system in my 4 door Ute consists of:

-Pioneer 7350 Headunit Has 6 RCA outs,2 been sub out
-Audio strata 4 x 50wrms amplifier (bridgeable)
-V12 2 x 170wrms amplifier (bridgeable)
-6.5" infinity Kappa components 90wrms (front door)
-6.5" infinity Reference components 90wrms (front door)
-6 x 9" JVC speakers 50wrms (back door) not hook up
-10" Exile shallow mount subwoofer 300wrms behind back seat

I installed all this myself,i have the 4 channel amp running both sets of components and the 2 channel amp (bridged) running sub which is mounted behind back seat as i have a ute, no boot.This set up has very very clarity and bass and sounds very nice.My question is. Can i run the 6x9s off the headunit because i tried but no sound produced,is it because im using all 6 RCA outputs? if not what would likely be the problem? Do you have any recommendations for me to change the set up?

Answer
"is it because I'm using all 6 RCA outputs?"
It may be.
There will be data in the manual about what is possible with the fading and which internal/external power amp combos are available for you to use.
If they are wired correctly and the wires are not shorted anywhere AND the 6x9's are functional..it must be the headunit settings.

I am not really sure what your intentions are but it sounds like you are very happy with the system as it is and you want to add that extra touch of audio quality to it.
Two channels of dedicated midbass is the next logical step.
If you are indeed now seeking some dedicated midbass to smooth the transition from the subwoofer to the midranges, the 6x9's might be a worthy endeavor but once you get their output to match the rest of the system, you really need to have a bandpass crossover on them in most cases or they just start taking away from the overall clarity.
If you plan to use the deck power amps, you will need to use passive, bandpass crossovers on each 6x9 (or whatever you end up using).
At best, those amps in the deck are about 15 watts RMS so the deck power is not quite adequate for midbass. I would suggest another 50x2 amp if your alternator can handle it.
If you are just fiddling with it..outside of the fun factor, you may be best off not doing so :)

I hope this helps and let me know if I can be of further assistance.

jm