I have used an Airport Express to stream music from iTunes on my iMac to a Denon AVR3200 for a couple of years at least. After I moved last fall, I reconnected the same AE to the same receiver in the same manner it was before, which is connecting the AE to the VCR2/Aux input on the back of the 3200. I can still stream music just fine, but here's the crazy part. I have to switch the Denon's input to the VCR1 input to hear music. And to make it even more maddening, I can hear the music through the CD, phono, and TV/DBS inputs, but not through the VCR2/Aux inputs where the AE is connected. If anybody could offer any insight into what might be causing this weird phenomenon, I would sure like to hear it. 
I know now that it's the receiver that has the problem, not the AE. I plugged my iPod dock into the same inputs, and I still get music from all inputs, except, of course, for the VCR2/Aux where the iPod is connected. The mystery continues.
I know now that it's the receiver that has the problem, not the AE. I plugged my iPod dock into the same inputs, and I still get music from all inputs, except, of course, for the VCR2/Aux where the iPod is connected. The mystery continues.