[Bookerv12]

Hi,

The pre amp is not active on the trs input.
The trs comes after the pre.
The gain control being active has nothing to do with the mic pre. It simply becomes a variable control between -10 and +4.
The button simply switches between inputs.
Just remember.....the pre section brings your signal up to line level. That's why the trs comes after the xlr input...it's bypassing the pre amp.
You have to be plugged into the xlr to access the pre.
There are a bunch of real good reasons for this.

Good luck