Need some wiring help...

The installation going in my wife's car (2015 Hyundai Sonata) with a goal of retaining factory radio. The dash unit sends signal to factory amp via SPDIF for all features. I will be grabbing the signal after the factory amp. Plan on testing this weekend for how the signal looks coming from the amp, but the current outputs are Front Mid and Front High, Rear Full and Subwoofer. The plan is to use a Helix DSP.2 for signal processing going to Arc amps and some Hybrid Audio components up front. The original plan was just grab the Front mid/high and sub into the DSP and continue to run rear off factory, but am hearing that I should time delay the rear for proper tuning and this creates an Input problem. This is not a competition vehicle or anything like that, just want some good sound. So my questions are:

1. Do I need to DSP the rear speakers?
2. If so, and retain fr/rr balance control, do I need to Sum the Front Channels? (I have an LC7i that I can sum the channels with)
3. Should I not worry about retaining fr/rr balance as I really never use that anyway? (This would allow me to just use the Front mid/high and sub as inputs to the DSP.)

My options are:

1. Just run the Front mid/high and sub high level input into Helix and output all channels (front mid/high/rear/sub).
2. Run the LC7i for Front mid/high and sub summing into the Helix and output all channels. (Not sure about converting the rear into low level for the Helix)
3. Run a JL Audio Fix-86 for all inputs and output signal to the Helix.

Would like to keep the system simple, so if I could just use the DSP and not any other items, that would be ideal.

System:
Factory Head Unit to factory amp to
Helix DSP.2 to
Arc Audio XDi 600.4 to Hybrid Audio Imagine Components front
Arc Audio XDI 1100.1 to Audiofrog G10D4 or possibly 2 Pioneer subs
Not sure about small amp or speakers for rear doors. Would prefer not to have to buy anything else.

Thanks ahead of time for all your knowledge!

Anyone wish to offer some assistance?

Helix DSP.2 has 6ch of inputs. if there's no shenanigans w/ all passes or time alignment on the factory outputs, you could just input them directly to the dsp. do all 6 channels (front mid+high and rear)

you can use the helix's i/o mappings to mix down whatever you'd get from the lc7i and have one less device in the signal path.

• if front 4 channels comprise the full frequency range, you can mix them down to 2 channels and map them to 5-6 output channels. use the rear channels for rearfill shenanigans down the road.
• if front 4 channels aren't all frequencies, you need the rear channels to complete the frequency response.

i'd leave the rear speakers unplugged until you can put them through the dsp.