Need Advice - Speaker Wiring Options

I have 9 speakers in my system (3-way fronts, rear fill and a sub) plus two amps that provide 9 channels of amplification, but my BitOne DSP only has 8 output channels.

My shop tried to wire all 9 speakers for a full active install by only using the 7th channel on the BitOne to send signals to both rear speakers and the 8th channel is being used to send signal to my sub. I can't get into the I/O interface of the BitOne without redoing everything from scratch, so while it is clear that mono signals are being sent to the rear fill speakers as well as the sub, I'm not sure if these mono signals are combining left and right signals, or if they are only transmitting left side signals to the rear and right side signals to the sub.

Bottom line, I'm not happy with the results. It could be a phase issue, but they said they double checked this.

The most likely alternative to avoid this mono approach is to power the rear fill directly off the factory HU/amp, but this will not work because I will need to use the HU volume controls in this scenario. This factory 8.4AN HU/amp appears to have dynamic EQ (there is overpowering extremely muddy bass at low volumes and it attenuates bass at higher volumes), so I can't de-EQ the factory programmed EQ curves in this system with the BitOne across the whole volume spectrum. I need to keep my HU volume fixed at just below its clipping point (24 on a scale of 38) and I use the remote on the DSP to control volume so my EQ curves stay consistent at all volume levels.

What has me thinking my less than satisfactory results has something to do with the wiring and/or phase issues is that when I put my 8.4AN HU in Surround Mode, the LFE response from the sub absolutely comes to life. Its a huge difference. Even my front 3-ways come to life, but to a much lesser extent than the sub. Others users of this 8.4AN system say the Surround Mode barely makes any perceptible difference. The system was tuned with the Surround Mode off. Alpine would not provide any specific info on what the surround mode actually does on the 8.4AN, but they did say on most of their units it only changes phase and sometimes crossover points.

So my question...is the wiring approach my shop used actually viable, and is it worth playing with phases and tuning as it is currently setup (mono signals being sent to rear fill and sub), or this approach simply not a good idea.

For those that may say this is a bad approach, do you have any better suggestions (other than ditching the rear fill or connecting rear fill directly to HU)?

Thanks for any help.

I would play with it as it can't hurt but really best way to handle the alpine system if you invested a ton of money is gut it and start fresh.

That's why I went with the new helix pro because in has 10 outputs. Maybe you can return the bitone? I was looking at those before I found the helix. I have a great supplier of the helix as well. Good luck. But I would have used full channels for the rear and subs and the. Combined the headliner speakers and center channel on dash,mor just disconnected those so everything else was active.

The headliner speakers and center are disconnected, I have Hertz 6.5XLs in the doors, HL-70 mids in the dash, HT28 tweeters in the sail panels, HCX165s in the rears, and. JL Audio Stealthbox sub.

I didn't even realize the Helix Pro had 10 outputs, that would have made this much simpler.

Probably can't exchange the BitOne at this point, but who has the beast deal on the Helix Pro?

Pm me. Maybe you can sell the bitone