Amarok has greyed out one of my audio devices. I'm sure when I started up it asked if I wanted to disable it as it was being used by Kaffeine at the time and I must have inadvertently hit yes. Any ideas how I might re-enable it? It plays fine through the other device though, so I guess this is more an academic question. Thanks in advance

Well, Amarok has done absolutely nothing, it doesn't handle sound directly, everything goes through Phonon.

The problem you show is due to you using Pulseaudio, this is the culprit.

We recommend removing Pulseaudio and using the xine backend for phonon, this gives the best results and doesn't remove entries in the phonon list.

You don't say which version of amarok you're using or which distribution.
Removing pulseaudio isn't the right medicine, because that might break dependancies.
Mostly it's a poor configuration of the distribution, which causes problems between pulseaudio and KDE.
KDE (not Amarok) is asking you to disable devices which aren't available; in your case the digital output.
To state it clearly once again: Amarok doesn't handle any sound by itself.
Devices are handled by Phonon. It uses your sound framework, which can be either gstreamer (kick it in the can) or xine (recommended).

m0nk