I'm looking to upgrade my speakers and add a couple amps. I have a 2015 RT with the base system(no amp). I've upgraded to the 8.4 recently, and now want to replace all the speakers, amp them, as well as add a sub in the trunk. Do I need to run something like a DSR1, or am I ok going from the head straight to the new amps? Or would I be better off with something else between the head and amps? I've been reading up for a few days on DSP's, LOC's, and I'm just not sure what I do and don't need.