Hello Yipykya.

I have TWDLE and using my Pinnovators SAM+ setup. No dropouts that I can hear.
Can you tell if the Cabinet speaker goes completely dead with the Back Box speakers still play??

What do you hear if you plug your headphones in when the pop bumpers are active??

Try some slight pressure on the CPU/Sound board up by the corner where the speakers attach. Gently apply a little pressure to the two heat sinks and see if the sound cuts out. The amplifier chips are attached to the heat sinks. I can send a picture if you need one.
I hope that helps,
Thanks,
Mark

OK try this!
Unplug the speaker connector on the little Pinnovators board that plugs into the CPU/sound card.
Leave the board plugged in and the RJ45 cable attached. Unplug the subwoofer 3.5 mm cable.
Test the audio using the headphones.
This will rule out a shorted speaker wire.

Can you make a short video of the problem?
Make sure to record the audio at the back box speakers and then the cabinet speaker. Hopefully it will reproduce good!

Thanks,
Mark