Spotify invests most of their dev time into finding more ways to advertise, interrupt, and be annoying to their free and paid users. There's little innovation going on there. Like Hulu/Disney+,Netflix - Spotify makes piracy fun again.<p>The difficulty is in having precise playback time. If you're a few dozen milliseconds off the music will be terrible.<p>Perhaps make it so every phone/computer device with spotify connected can control its one set of speakers either cabled or bluetooth. User selects "Group Speakers". It plays a fun tone where the app listens for the delay between the audio going out and the audio being received, finding the playback latency. Now that the devices know their playback latency they can communicate and play at the same time. As users do this with things like bluetooth speakers you collect that data and make it automatic for future speakers of that type. If it's out of sync just have a "sync" button to do it manually. People will figure it out.