LOC + Line Level Inputs?

I have a 2013 Hyundai Elantra GT, it has the normal factory radio, nothing fancy at all. I like how it looks and like its function and have no desire to replace it. Though the sound was never that amazing. I replaced all the speakers with infinity speakers which did help some but I had no bass so I spliced in a LOC behind the head unit and hooked it up to the rear speakers. This is the LOC I am currently running: PAC Line Out Converter I added a small mono amp and subwoofer and it has been working great and I have been happy with it for the most part. Lately I am starting to feel like its just lacking, not a sudden change I just feel it could be better. So searching the forums I am getting several guys pointing me to getting a small 4 channel amp that will fit up behind the dashboard. This one to be exact: Clarion XC1410 Amplifier My question is, if I got that amp most guys are just cutting the speaker wires behind the head unit, using the line level inputs and the connecting the out to the speaker wires which were just cut. Now that sounds easy enough, but no one on my forums has done with and had an LOC as well. Is this possible? If it is do-able should the LOC be spliced into the rear speaker wires, before or after the new amp? Thanks in advance!

The small clarion amp has hi level inputs so use those instead of rca low level. The LOC will be fine behind head unit just hook it up before amp.