[popsicle_3000]

I have the e92 HIFI system. Unfortunately with my first install several years ago I cut the factory harness to connect up the amps/DSP etc... I'm not planning on remaking it simply to connect a technic harness.
The prev DSP I had was an audison bit ten so only had 2 RCA inputs.

My new DSP (Helix Pro Mk2) has 8 RCA inputs.

Should I just stick with the 2 front R/L HU outputs or does adding 2 more channels into the DSP from the rear R/L as well going to add anything sound wise?

I believe the entire signal is present in the fronts. The Helix amp does have some smart feature or something I believe where it can sense when the HU is adjusting fade and will do it as well. That is the only reason I can see to put in the rear channels as inputs so I can control the fade from the HU (I probably won't be getting their DSP controller as it's about 500 AUD).