Originally Posted by Gordon Scott
If correct, that's a bit surprising.
All the signals on the jack must be single-ended, so any DC would affect the performance of a dynamic mic or headphone by applying a bias to the coil. It would certainly have to be current-limited to perhaps microamps, if only because the impedance of the circuit needs to remain high enough to get a sensible signal. Could headset mics normally be electret? Maybe.
I believe most are electret, as are the mics in the phones themselves. Single-ended makes sense given phones have a single power source (battery, usually ~3-4v).

Originally Posted by Rustyspoon#
This is not for pro recording or good quality backing. Just sketches for rehearsals with her senior chorus band. During actual concerts she plays live. Girls are not professional, just having fun smile I think the iRig thing would be ideal for her as it's the simplest form of getting analog audio to ipad. Much simpler than traditional interface.
Yup, I think the iRig or similar would be perfect. Cheap and cheerful.

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