I went to use my OP1 today and there is a constant loud low humming tone coming thru. I’ve been googling it, but have had no luck!
Is this through your monitors or the built-in speaker? And this is occurring without pressing any keys?
Try turning off USB charging.
You can get tones for effects on the master too. Punch with everything turned up for example. So turn off all the effects ( and master) too.