A peak at the MG10 manual and I don't see off hand how to prevent a playback/record loop if you connect the input and output to any soundcard since it does not have a way to separate the channel routing of any channel. I think you would have to keep your speakers connected to the soundcard line out jack. Which means you control volume via soundcard properties or your powered speaker. Or, if it's connected to a home stereo you can use it's dials or remote after you make nominal settings in the soundcard properties.

For the part 5 years or so I have been using a MG124CX (not usb) as my interface either directly to my built in line in and line out jacks or along with a stand alone USB audio interface. However, it has Group Sends, Stereo, Sends, FX Sends, Headphone Send, Pre Fader Listening routing and so on. These features allow me to press a few buttons to switch the soundcard or interface input/output back and forth at the press of a button or two and prevent looping and feedback. I used to use a little Behringer 10 or 8 something or other that allowed me to do something similar. But, I don't see these features on the MG10.
Maybe someone using that particular mixer knows otherwise.

Okay, now I'm really out of time.

Last edited by Tobias; 02/10/17 07:29 PM.
Does the noise in your head bother me ?