RE: [stationpro] Icom connections and speakers
You’re defeating the purpose of the StationPro by connecting individual speakers to each of your transceivers. You can do that but, as you note, you’ll have to turn the volume down for the radios you’re not using. My suggestion is to pick the speaker that sounds the best and run all three radios through that, via the StationPro. Then use the headphone jack on the StationPro. It’s much more convenient and will also free up space on your operating desk.
There’s no problem running the Heil mic with your Icom radios (I used a Heil mic with my IC-7700 and it worked great), so long as you put a 1uF blocking capacitor in the mic+ lead on the pod to keep DC off the Heil mic element. Icom mics require a voltage on the Mic+ line, but that will damage other kinds of mics.