I just bought a Sonos Arc to replace the Playbar. My current set up is Arc, Sub, Sonos 1 & One SL as surround speakers.
After switching over to the ARC I can't really tell a huge difference from the Playbar. It sounds good, but so did my Playbar. I've tried some Atmos movies through my 4k firestick. When playing atmos movie my Sonos 2 app is telling me it's playing Atmos (movies through HBO Max). I changed a setting on my tv which allowed the Atmos designation to show up on my Sonos 2 app. The fire stick also is set for best sound available.
I’ve moved the ARC so it's about 4” below the tv and in front. It's about 5 feet from the ceiling (flat). ARC is about head level when sitting on couch which is about 8’ away or so. I tried true tuning. I've even played with the Highs setting for the Arc and never noticed anything by doing that.
Do I need to unpair my rear speakers and just do speaker and sub? I’m not sure if im missing something here. Im disappointed that the sound quality doesn't really feel upgraded considering the price I paid for a new Sonos Arc compared to the Playbar I used to have.