Steinberg UR12 noise

I have a steinberg ur12 sound card, when I adjust the gains, the sound of the microphone starts to make noise (even if the microphone is not connected)

please help!

Hi and welcome,

You say it happens even when the microphone is not connected. Have you removed the microphone cable/s from the input socket as well?

Is there any noise with the gains on zero?

Are you using the latest drivers for the interface?