That depends on the capabilities of your audio panel - if it has inputs for 2 COM radios. While the SV-INTERCOM-2S has two COM radio inputs, we no longer recommend that you use it the second COM radio input. If you do choose to have two COM radios installed, we recommend the use of an audio panel from PS Engineering.
If you want only one COM to transmit at a time (including two SV-COM-C25s) when you push your PTT switch, then wire a Single Pole Double Throw (SPDT) to your PTT line. The PTT switch goes to the middle terminal, then each of the other terminals goes to the PTT line of the COM radio. Flip the switch one way, COM X transmits. Flip the switch the other way, COM Y transmits.
I have a Icom 210 that is noisy and Icom have been no help in solving the problem.
What I am proposing is to remove the Icom and fit two SV-COM-C25 radios. I know each radio can monitor two channels but can the system be wired so that both radios can be monitored simultaneously (i.e. four channels) but only transmit on one channel?