aftermarket amp and sub question

Guys,

I recently installed Infinity Reference 6020's all the way around along with a serious amout of b-quite. The sound is A LOT better than the stock JBL 'premium sound', but i'm not happy just yet. The highs, IMO, are just too harsh to really enjoy. That is with the crossovers set to -3db and the treble moved down to about mid way in the HU. If I move the treble down to an acceptable 'harshness level', then everything sounds muddy and much worse than the stock JBL...so more EQ adjustability is needed.


My thought is to add a Zeus ZXi 4-Channel Amplifier ZXi6406 along with a Clarion EQS746 7 Band EQ. Now I know all of this will sound much better than what I have now, but I don't want to give up any sort of so stock functionability when it comes to NAV/BT.

SO here is my question: on a 2008, If i use ONLY the rear JBL outputs to feed the EQ/Amp, will I lose the BT/NAV? OR will I have to sum the two front channels and use that to feed the amp in order to retain voice nav?


I NEED to figure this out before I buy anything else. ANY help is much appreicated. THANKS