20dB is quite a bump. I think I have a similar increase in low frequencies in my family room and I always thought it was my modest subwoofer that was not up to the task. I suspect after applying the 976's PEQ settings your bass/LFE will be much less boomy and I'm hoping to achieve similar positive results.
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AvFan
Outlaw 976 | ATI 2005 | M&K 850s Left, Center & Right, Surround-55s, MX-70B Sub | Harmony 950 remote | Panamax 5100 | OPPO UDP-203 | LG OLED55B7