Emu Emulator II - mix out distorts

Hi there, got an issue with the mix out on an Emulator II. It sounds like the DAC is being overloaded. Almost a bitcrusher like digital distortion. If I play a single note very gently (low velocity) it sometimes sounds clean(albeit too quiet), but otherwise it distorts terribly. All other outs (1-8) work fine.

The service manual makes no mention of DAC trims, so not sure how to go about fixing. Anyone have any experience with this?

Cheers!