I am sorry to report that we have discovered a problem with some of the power supplies which I have shipped out with Dexter.
They look like this:
The symptoms include a buzzing hum heard over the game speakers and possible lock-ups of Dexter itself where the system needs to be restarted.
Here are two replacement power supplies that I've tested and verified work much better:
This one by imbaprice and this one by TICTID.