I now have Alpine CDA-9815 headunit with CDT ES 620 ( 150 W rms, 92dBs ) Eurosport component speakers for the front . I also have the Classic series CL-61a components for the passengers in the back of my Toyota van. I've also got a JL300/4 amp from a friend. I have a few questions:
1. I am the driver so the front is much more important to me. I am thinking of bridging the JL amp to give 150 W rmsx2( 1-4 ohms)to drive the front speakers, then use the internal amp of the CDA 9815 to drive the rear speakers( 27 W rms ). The power for the back speakers is not optimal but it probably can drive the speakers loud enough for the rear passengers. With this much discrepancy in power between tne front and the rear, I have problem conceptually to see how the headunit can integrate different amplifiers for the front and back speakers seamlessly, perhaps someone can explain this to me? Also would this set up be OK.
2. Or Is it better ( quality of sound-wise ) to just use the 9815 as the Preamp and the JL300/4 ( 75W rmsx4) to drive the front and back speakers?
the head unit doesn't know how much power the amp has. it just puts out a line voltage through the three sets of RCA lines. balance will be set by you at the radio using the fader. try bridging the amp and see how it sounds. if its more than you need, then run it as a 4 channel for all four channels. see what you like the best.