The Squeezebox Duet (maybe their other devices too) 9VDC power supplies always seem to fail. I have two receivers and both power supplies failed. Factory replacement power supplies are no longer available and if they are they will probably be expensive and fail. I went to a local Microcenter store and purchased new 9VDC power supplies. The connectors did not fit into the SB, so I cut the connectors off the old power supply, cut the connectors off the new power supply, and soldered the old connector onto the new PS wire. A bit of soldering and heat shrink tube and all is good again. Be sure to use a voltmeter to verify proper polarity at connector. This is pretty easy, but if you dont have the skills find some kid who is into electronics to fix you up.
+1 for the guy who mentioned the Bluesound Node 2i. I replaced my SB with the 2i and love it.