My PC is multi-user.  If one user is logged in and playing music in Amarok, and then I log in and wish to pause their playlist and start my own, how can I do this?  Ideally I'd like to give each user and easy way to pause each other's Amarok player.

My first thought was to use dcop, so I've tried the following:

su username -c dcop amarok player playPause
and
su username -c "dcop --all-sessions --user username amarok player playPause"
and
dcop --all-sessions --user username amarok player playPause

but in each case I get the following error:

DCOPClient::attachInternal. Attach failed Could not open network socket
DCOPClient::attachInternal. Attach failed Could not open network socket
ERROR: Couldn't attach to DCOP server!

Does anybody know how to get aound this problem, or if there is an easier way to do what I want?