Until today I didn’t know this, but it seems to be possible to control the volume on Spotify Connect from one device to the other, say this thread on the Spotify Forum. It works only on Android, not on iPhone. But, there are a lot of devices where this still doesn’t work, like on all the devices I have. I found out it works only from my Moto G phone to my laptop (with Spotify Beta with Spotify Connect support. Strange… Has anybody else a good experience with volume control on Spotify Connect? Or does anybody know why it’s working on one device, and doesn’t on the other?
I’ve got a reply from the Spotify Support team; volume control with Spotify Connect from mobile to mobile doesn’t work at the moment. They don’t know if this feature will be implemented.