On a 2008 with the premium JBL system, If i use ONLY the rear JBL outputs to feed and aftermarket 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?
If you are planning on a complete audio system revamp......The JBL amp processes the BT/NAV audio seperately, so if you replace the JBL amp, or tap only the rear channels for all your new audio, you will lose BT/NAV stuff. If you keep the JBL amp, and run all the outputs to an audio processor like CleanSweep, or Alpine's solution, then add an aftermarket amp, you will not loose the BT/NAV. If you are adding an amp for a subwoofer, just tap the rear channels with a LOC for the output to the new sub amp.
