This is probably not the answer to your question but it's my twopence worth anyway ;-)
I've got a Cyber card but only one monitor connection on it.
What I've got is a monitor/TV that I've got the standard Miggy output connected up through the standard monitor out through a scart lead into the video and audio in.
I've got the Cyber output connected to the monitor in and bridged the audio in just in case it's required.
I also use ModePro (from Aminet) it promotes all legally written software to use the Cyber output.
Any that don't work (mostly games) that way I just press a switch on the monitor to switch over to the other input.
Dave G 8-)