Monitor out level - Zed 10 FX

RCA phono monitor outs to Powered PA. Monitor source set to mix. Monitor out gain knob turned all the way down to infinity. Yet, I still have substantial signal/volume coming through the PA. What am I missing here?

I was previously using the main XLR outs to PA and had no trouble turning my room volume all the way down/killing signal with the main mix knob. However, the main mix knob affects USB out gain when recording via USB. I just want to quiet my monitor in the room without affecting the recording. I thought monitoring from the monitor outs would solve my problem. Is this the expected behavior?

Nevermind, please disregard. I had a pre-mixer signal sent to a guitar cab stacked on my PA. This post should be changed to “How do I delete a forum post?”