High level inputs OEM HU

I'm installing 2 identical powered subs using high level (HL) inputs spliced into factory wiring (via speaker adapter) and I'm experiencing an interesting issue that I'm not sure how to troubleshoot.

The subs have HL inputs that use the signal for remote turn on. Driver side works just as it should - powers off when HU is off, has full sound to it using L-/L+ speaker inputs. Passenger side, however, does not power the sub on with the HL inputs and it doesn't sound anywhere near as powerful using the exact same dial settings (Low bass boost, cutoff and gain) with R-/R+ speaker inputs. It's not the sub itself because I've swapped them and issue is the same regardless. I even removed the adapter and went direct to the factory harness to test. I've swapped the power cables as well so I think I've removed all variables except for driver's side using L-/L+ inputs because it's using the L speaker and passenger using R-/R+ because it's on the right side.

This essentially allows me the ability to fade L/R and have each sub independent (to test, not for any specific purpose). The sound difference is significant. I even hooked up driver HL to the passenger sub using the L-/L+ input and it is the same issue.

I know the audio signal is going to the sub because it's giving bass, just not as much. It's overpowered by the driver's side even with passenger dials cranked and driver dials mid-way

I would think, if anything, passenger side would have more power to it since it's technically farther away but at the very worst, it should be identical. I hope this comes through how I want it to. Any suggestions?