Comment 8 for bug 961002

David and I have discussed this, here are the findings :

The bug arises from an issue with pulse whereby the supported profile list of a given device changes at runtime so for example (and also specific to this case for this bug) a device which supported a surround profile at startup for some reason during the lifetime of that pulse instance does not support surround any more. But there is no signal or notifications from pulse to say that this profile is no longer supported on this device. Therefore when the user goes to swap to the surround profile, the new sink that should be created by a successfully profile swap does not. And correctly the UI swaps back to the 'default' sink/output.

The UI though should notifiy the user that there is a problem with this device.