Hello, what is the intended purpose of the design? The physical interface can be quite simple if you are just looking to eliminate using 2 connectors for the mic/headphone. The broadcast industry standard is a 4 or 5 pin XLR connector which is reasonably durable and offers a much more reliable connection than 2.5mm or 3.5mm phone jacks. As for the electronics with which you will be interfacing with, more info is needed. Generally speaking a dynamic mic circuit will not work with a condenser mic because of the lack of power on the line. A dynamic mic may work with a condenser circuit, but the power will be shorted through the coil of the mic. Without a current limiter of some sort this may damage the mic and or the circuit. A piezo mic would probably work in either circuits, but another factor to consider is the impedance of the various mics. Piezos and condensers are high impedance and a dynamic is low impedance. Mismatching can result in significant level differences from one combination to another. If you were designing the circuits you could have switches to change mic types. Thats about all I can say without an application to go on. -regards