Neither Apple Music nor Spotify have to first check across your network that Sonos speakers are hooked up. That being said, one of Sonos’ recent updates to S2 has certainly increased the speed at which the controller starts up. You haven’t defined what you mean by ‘slow’, so it makes me think there is something going on in your network that is slowing the controller’s ability to ‘find’ your system when you boot it up.
Have you submitted a system diagnostic within 10 minutes of experiencing this problem, and called Sonos Support to discuss it? Don’t post the resulting diagnostic number here, they get sensitive about GDPR.
There may be information included in the diagnostic that will help Sonos pinpoint one, or even several issue(s) and help you find a solution.
When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.
Apple just recently released the SDK for public consumption to allow AirPlay 2 to transmit Atmos to third party devices. While Sonos doesn’t often tell us what they’re working on, I’d expect that to be in an upcoming update, and mentioned in the release notes, since it is a fairly ‘big’ thing.
No matter what, Sonos will always be checking for an existing system first, whereas service apps don’t have to.
