A bit more data. No input, 1 XLR out from ANA1. Power up unit from cold, no ring/whine. A few minutes later as machine heats up ring starts and gets louder. Sounds like hardware?
Could be – hard to tell without seeing it. Probably not.
1) does this apply on all presets ?
2) does this apply on dsp bypass ?
3) can we assume that your gain settings are those you would use with your instrument ? Put enough gain after any digital equipment and you will hear bad things.
4) can we assume that you have done as requested and set up your signal level or input gain to light all the green leds ? If not, DO IT !
Otherwise, if it is under warranty, you should contact email@example.com about sending it in. If not, contact them about having it serviced.