Thanks KillerKiwi - earcandy does seem to provide the behaviour I want (will take a look at it in more detail)
As you say, this really "ought" to be fixed in PulseAudio and/or Ubuntu formally (which could involve earcandy being installed and started by default). On my Mac, I can just plug in the same headset, and the audio switches transparently. It's crazy that this is not default behaviour on USB headsets.
Thanks KillerKiwi - earcandy does seem to provide the behaviour I want (will take a look at it in more detail)
As you say, this really "ought" to be fixed in PulseAudio and/or Ubuntu formally (which could involve earcandy being installed and started by default). On my Mac, I can just plug in the same headset, and the audio switches transparently. It's crazy that this is not default behaviour on USB headsets.