I just bought a few days ago a amp Onkyo CR-N765 for Spotify Connect. I was able to stream from the Spotify app a few times. But now, the référence of the amp doesn't show anymore.
I consulted the list of devices compatible with the Spotify Connect. This specific Onkyo amp is not referenced. But I'm not sure that the list is complete since a friend of mine use Spotify with a Yamaha not referenced in that list.