Thanks for your response GarsuMene , I'm relieved it isn't just me!! My concern was it is hearing damage loud. Interesting you are using an RME interface too. It is stable with MIDI and audio cables but I haven't got the plugin then so that's not ideal. My SPDIF's are optical so I can't use your fix. I'll try going back to USB and configure audio over the audio outs rather than USB.
I might have an experiment with Ice9 plugin on the Cubase outputs to set a max dB level too.