JimboG:

I am a new 990 owner, but isn't what you are describing the "dreaded" double bass (assuming your front speakers can go lower then the cutoff frequency for the subwoofer DSP)?
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Living Room 24x18 open 1/2 flight up to a raised dining room/hall 24x12
Outlaw 976 pre-pro running 5.1 system
Outlaw 750 for Artison Masterpiece LCR and 2 NHT SuperZeros rears
Velodyne Servo FX-1200
LG OLED65C8PUA via HDMI2 to/from 976 HDMI ARC
Roku Ultra
Samsung BD-D5500 BluRay
Amazon FireStick 4K to 976 Aux HDMI input for Amazon Music Ultra