As long as the siren has a Power input, and uses trigger wires to activate a tone, you can use it without a problem. If the siren requires the output of the controller to run the siren, then a Relay will be required. Each output on the 4200 is good for 5a
Dang! I was kinda hoping i could just solder in a couple wires on the back side of some switches and be done with it. I like the attractive cost of some of the older models on ebay, but I'd surely wind up with a nest of relays and wires running into the box.
You might be happy with a Unitrol 80K or Omega 90 instead of a Touchmaster. Both lend themselves to remoting. The Omega 90 will offer you a wider range of tones and functions than the 80K, but it will also likely cost more.