I have 2 Play 5 (Gen: 2) in stereo with a sub gen 3 for lots of punch.
But I figured out, that when I change the volume on my left speaker it doesn’t change on the sub, so if you put it on 10% in the app then to 0 on the speaker, both of the speakers will go quiet but the sub still plays the song
That doesn’t happen on the right speaker or the app
Not a major annoyance for me, but interesting and something someone should look into