Dual TPA3116 board for the Breeze chassis #1

FOLLOWUP: This board has HORRIBLE noise floor and here's how to fix it:    • Dual TPA3116 board: Fixing the AWFUL ...  

Some off-hand measurements and hacks on one of the dual TPA3116 boards available for the Breeze Audio chassis.
The performance of the board seems to be generally acceptable, but the low-pass filter for the subwoofer output has a very silly filter topology, making it somewhat useless in its standard issue. I take the time to change it around a bit to make it better.
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