Hi, finally getting around to updating the speakers in the wrx.

Adding a new set of splits to the front, 4ch amp, sub and new components to the rear. I'm keeping the factory HU for now.

I plan to run the front splits and the sub off the amp and keep the rears running off the HU.

Question is, I'm not really sure how or what I need to get the sound from the HU to the amp. I know I need a LOC. But I'm not sure if I need something like the PAC SOEM-4 or the PAC LP7-4. And how does this fit in with my proposed setup?

I'm guessing I take the front speaker wires from the HU and split them making 2 sets of left and right. These then connect to the 4 LOC inputs. Then using 2 sets of RCAs from the LOC outputs, connect to the amp inputs.

Amp then connects 2ch's out to the front splits and bridge the remaining 2ch's to the sub. Obviously amp has a power kit, remote turn on from LOC etc too.

The rear components are a simple speaker swap, so nothing needed to be rewired/reconnected. Is it even worth swapping these given the relatively low power output from the factory HU. I was looking at getting Pioneer TS-A1675S 3-way 300W peak/50W RMS.

Does this all sound right?
Are those 2 LOC's suitable for the job and should I prefer one over the other?

Is there anything else I'm missing?

Thanks for your help!