Subwoofers often generate ground/hum loops.
To fix it, only one component in your system should be grounded through the AC cable. The remaining ones should float through 3 prong to 2 AC adapters, otherwise there will be a ground loop.
For safety reasons, I suggest that you ground the BAT amplifier through the AC cable, it is your component that draws the most current.
Also, disconnect the ground wire between subwoofer and preamp, it forms a ground loop, because the ICs carry signal ground from one component to the next.
Also: if your amp is a bridged design, the speaker (-) lead is floating and should be left floating. DO NOT ground the subwoofer high level (-) input.
I hope this helps
To fix it, only one component in your system should be grounded through the AC cable. The remaining ones should float through 3 prong to 2 AC adapters, otherwise there will be a ground loop.
For safety reasons, I suggest that you ground the BAT amplifier through the AC cable, it is your component that draws the most current.
Also, disconnect the ground wire between subwoofer and preamp, it forms a ground loop, because the ICs carry signal ground from one component to the next.
Also: if your amp is a bridged design, the speaker (-) lead is floating and should be left floating. DO NOT ground the subwoofer high level (-) input.
I hope this helps