the VXPocket's analog gain adjustments are a royal pain in the ass. it's in the driver setup, not the system mixer or anywhere convenient.
they may have fixed this in recent driver versions - i sold mine in august. but when i ran self-powered mics > VXPocket, i had a hell of a time adjusting it. and it sounded way worse than mics > M1 > SPDIF > VXPocket to me.