UR12 wave of hissing on both inputs

I’ve been using the UR12 quite happily for a few years, (Cubase 9.5). A few days ago I started to get a constant low hiss off the input 2 jack, and a very low signal being taken in, (not going to headphones). The Mic input 1 seemed okay, but it now has a low hiss also, however only when sending a signal, (speaking. singing) through the mic. I’ve tried various projects, with different settings, in case it was some random fx issue and I checked the inputs to the DAW etc…
The UR12 still functions for playback to speakers and headphone, with no issues.
Any ideas?