2nd comm (non Dynon) in Skyview/HDX System?

In a plane I'm helping out with (and another down the road), I'm thinking about the possibility of connecting a non-Dynon 2nd COM radio to the Dynon audio panel & system.

In https://vansairforce.net/community/showthread.php?t=121697&page=2 there's a simple idea to provide a minimal audio panel with 3 switches.

Or, on page 16-14 of the HDX install manual there's a diagram for connecting two radios. But it isn't clear how you actually select the radio, other than the manual radio TX select switch. Do you control the audio with the radio volume controls?

The 'why' isn't important, but two possibilities...
1) can pick up lightly used COM radios from Europe as a result of their need to upgrade (for less than a new radio)
2) to connect an IFR navigator that has a build in COM radio (i.e. Garmin 430W or newer).

And I know for VFR use, if you have a hand-held you really don't need the 2nd radio.

So, putting those arguments aside... has anyone put this together? Tips?

blaplante said:

….But it isn't clear how you actually select the radio, other than the manual radio TX select switch. Do you control the audio with the radio volume controls?

Click to expand...

Exactly as you described^^^^above.
I don’t have a Dynon panel but use a similar arrangement. #1 com is a flip flop, I use #2 almost exclusively for atis - just turn up the volume to hear it.