As suggested, make sure your amp attenuator knobs are cranked up to the right enough to where you’re getting several lights flickering during bass content. Your gain in the software being +6.8 and the huge +12dB and +8dB PEQ you’re running tells us something is obviously way off, possibly in the gain structure; however, these amps have a lower input sensitivity than most pro amps and don’t need really high voltage input to reach their full potential or at least solid output.
Also, have you modeled the PEQ you added at 20Hz to make sure it’s safe? Because +12dB near tuning seems like it’s probably way beyond that driver’s limits in a Devastator, but I’m just basing this off modeling of the LaVoce for my 10 cu ft cab which is a different animal.
The phase at 180 is ok, as Behringers I believe are still inverting this feature in the software.
Do you have REW or the ability to measure its response in room?
Speakers: PSA MTM-210T x2, MTM-210C, MT-110SR x2; Atmos-SVS Satellite x2, DIY Volt-10 x2
Subs: PSA V1801 x2, DIY: 18" RSS460HO, 15" RSS390HO x2, BOSS w/JBL CX1200 x6
MA’s: Crowson Tech x2
Processing: Denon X4200, NU6KDSP, 3KDSP
Video: Epson 3700; Screen: Silver Ticket 106" High Contrast