Alright here is the run down....
Dxi Components in the front and rear doors.
PA660 using line level input harness
Auxiliary cable out from the pa660 to the pa880 (verified this works. Front channel acts as an output. Though a slight volume is used from the front inputs which is retained by gain adjustment)
PA880 aux input powering a dxi112 12".
Factory Head Unit is in a Kia Sportage 2011.
Here's my issue. Low hiss for all speakers when the system turns on and nothing is playing. I assume this is from using the line level instead of all RCA connections. I can live with this. My fade and balance controls all work except for the front right. If I fade all the way front and balance on the way right sound comes from all speakers! This does not happen on any other speakers when faded to them. Really strange, I've never seen this happen. Verified by multiple people that my system should be working as designed and I've stumped all of them with this issue. I went to the dealership and tried other Sportages and all of them work fine so it's not a stock HU thing.
So yeah, the RCA fronts do function as an output though Polk CS was unsure and th manual says only the 880 has outputs. Yes I've tried unplugging the rca's to see if that was causing the fade/balance. It was not. My next test will be moving speakers from the output terminals and determine if it follows a specific channel/wire. Wanted to pose the question here and see if anyone has ever experienced this?