JQ8400FL-10P MP3 - Nasty sounding shutdown

Hello

I have several JQ8400FL-10P MP3 modules here. Wired up and working fine.

But, at the end of each MP3 ‘clip’, there is a random, but sometimes significant dirty clipping/rasp as the module ends the file.

I am guessing it is a bad ground plane issue (don’t think they are designed all that well).

Supply is smoothed to within an inch of its life, so that seems fine.
Caps added directly across the PCB on the supply as well.

Resistors on the TX line into the module.

Tried a short lead from the USB connector housing to 0v… no difference (I suspect it might be the USB port power that is creating the issue).

Any ideas on how I can eliminate this issue? I am out of ideas (already zapped one board with my random capacitor prodding).

PDF attached if its any help (which I doubt).

JQ8400+Audio+Module+Manual+V1_3.pdf (449 KB)

OK. A ferrite coil on the USB lead (to the USB stick containing the MP3 files) has almost totally removed the noise, so it is the USB supply