Sound showing in meter when all recording devices are off

I'm very new to DAWs in general and am trying to set up PreSonus Studio 1 free (as well as Sonar LE which came with a FX pedal).

I've been able to identify all Recording and Playback devices by trial and error in my PC settings. I now ONLY have my Wharfedale 1202FX USB mixer showing/registering within the DAW and PC. I then tued the volume right down on the mixer so I can hear nothing in my headphones.

I am still getting the recording meter for a track bouncing up and down and I can't think what could be causing this with all recording devices off. Nothing is showing in the PC Sounds area.

I'm just looking for some suggestions without going into fine detail of PC spec and DAW versions if that's possible.