JBL system amp upgrade help

I am want to start with installing an aftermarket amp and maybe install some component sets later. The main 2 options I can see is the
Kenwood Excelon P-XR600-6DSP with maestro ar or using the Dsr1 with aftermarket amp of choice. Any pro and cons to either? It looks like the stock JBL amp is 8 channel. How are you guys wiring the 5 channel or Xr600 6 channel amps? Are you putting multiple speakers on a channel or not using all the speakers? Thanks for any help I can't take this crappy JBL much longer.

 

Im running a 5 ch amp on my jbl sequoia. The front speaker are component with external crossover. So i run channel 1 and 2 for front, combine all the rear left speakers to channel 3 and all right speakers to channel 4. Channel 5 is running the subwoofer (12inch infinity REF1200S downfiring enclosure).
Center speaker is disconnected. Corner speakers are replaced with the tweeter from the component set.