I’m pretty sure YouTube videos only play in stereo, not Dolby Digital Plus. What specific music are you playing in Dolby Digital Plus? Are you using the YouTube app or YouTube Music?

So

YouTube music app on phone airplay = stereo

YouTube music on Sonos app = stereo

youtube app on tv = Dolby digital plus 2.0 with arc and Sony tv. With the tv the surround speakers, they are just ambient

but I have another room with playbar and surrounds, if I multi cast it to that room all speakers are full music and a lot louder than stereo playback.

literally volume 10 with Dolby digital plus playback is equal to 24-26 on stereo playback.

also have a five in another room and the stereo playback vs dd+ is night and day.

It looks like your TV is just converting the original stereo audio from YouTube to two-channel Dolby Digital Plus. So if you want “DD+“ audio from YouTube, you need to use the YouTube app on your Sony so the TV can do the audio conversion.

Argh dammit, thought so.

So is stereo the best that is on offer currently via streaming services? Or is there another way/app that can give Dolby anything?

The majority of music offered on streaming services is in stereo. That’s just the way most music is mixed. But streaming services like TIDAL and Apple Music now offer some music in Dolby Atmos. Apple Music even has some albums in “Dolby Audio” which is basically 5.1 audio. Whether or not you can listen to Dolby Atmos music will depend on your setup (TV model, streaming device, subscription level).

Sonos has recently announced that users will soon be able to listen to Dolby Atmos music through Amazon Music directly from the Sonos app which is a first. Currently you need to run a music app from a native TV app or external media device like an Apple TV 4K to listen to Dolby Atmos music.