I found this article (Link) that addresses the less than stellar vocals volume in some Atmos mixes, the quote is from the Atmos Renderer section:Listening now to The Church-The Hypnogogue.
I like probably most only have The Church-Starfish in my collection.
This is real good. Great big sound. Atmos is powerful.
One small disappointment is vocals, seem a touch to recessed. There is no center channel action so vocals come via front left and right speakers.
I turned up both front and left 2db each and helped, a song like Track 3-I think I Knew when music goes quiet then no problem. Also reading lyrics as the song goes, without lyrics I would be straining to hear lyrics. Track 3-Flickering Lights vocals better again in the softer spots. Maybe I should finish the listen before commenting, but first Track 1 & Track 2 where hard for me, vocal wise.
But as streaming Atmos goes, really great!
EDIT: Finished complete listen and for the most part I do think the release benefited by the db levels being raised at front left and right, for vocals only. All systems are different, so this info likely just for me. Really good Atmos release, most importantly music and lyrics.
According to the author:
What I found is that Spatial Audio doesn’t seem to like mono sources that are panned front left/ right with no center channel. I’ve loved 5.1 music mixes over the years, but how people mixed those was all over the place, and often the center channel was hardly used. This may sound great in 5.1 or even on an Atmos setup, but in Spatial Audio, that lead vocal that didn’t make use of the center channel may sound low and distant compared to the Atmos mix and even compared to the Dolby Binaural mix. That was the exact issue I had with so many Spatial Audio tracks that I have listened to, and I couldn’t figure out why some songs sounded like that and some didn’t. Now I know why. You can pan left and you can pan right, but if you have that mono element coming from the left and right without using the center channel, you may run into this issue with Spatial Audio.