Hi Rogue. Sorry for delay..Work...
I am using Raspberry pi powerblock, plugged into the picade hat, thats stuck on top of the pi3. Slightly raised I guess as its on a pibow case too.
There is a heat sink on the pi, but it doesnt get near the picade..Not as far as I can see.
Nothing into USBs, only a 360 xbox USB controller for setting up.
All fairly standard.. What i can say, is that the sound is better now I have done a clean install, BUT I am still getting this overrun error. I have a speaker plugged into the picade, its probably a little big (8ohm) but regardless of that being plugged in or not, it doesnt make a difference to the error being seen when I shut down..
Maybe try a new picade? I never used to see this before, seems to have just come on..