So, after my trauma of Mame4All and my USB Soundbar I binned that approach and used a bog standard 3.5mm audio out instead (my cabinet is driving an old 4:3 monitor, no HDMI). Anyway, generally speaking the sound is OK but once in while it stops working – in the whole of Retropie, not just a single emulator. Reboot and its fine – which suggests its not the hardware.

Anyone seen this before?

Cheers

Mark