Have you confirmed with Brian what the two LEDs you see blinking indicate? If indeed, one is an indicator on the input, what does blinking mean? If blinks mean the input is being over driven, you must fix that problem before expecting any positive results.
Do you really listen at 80% of maximum on your Main Volume control? If you run only the Spatial Audio speakers, what dB level do you listen at?
Did you try the speaker level inputs to the Sub amps as Danny suggested? If so, what was the result?
Is it possible the Open Baffle configuration for the amps is in firmware that could/should be updated? With supply issues these days, would not rule out incorrectly configured amps regardless of marking. Have you asked Brian to exchange one or both of the amps to determine if you have defective amps?