Alternatives to the WS420 Mic

I went with a lower end EQ and the HSE which takes care of my needs.

Question is if I wanted to add a Mic to this setup, I could use the aux input on either the HSE or the EQ, but that would mean I would have to hit a button to turn it on and off. Is there such a device that would go inline that would mute the main input when it sensed input from the Mic then cut back to the main input when the signal from the Mic dropped off?

Thanks,

Dave