Yeah those A pillar speakers are used as the height channels for Dolby Atmos tracks, they’re only active when signal is being sent to them purposefully (the track was mixed sending certain things to the heigh channels). Only Tidal HiFI Plus can play back Dolby Atmos tracks. CarPlay cannot play Atmos tracks yet in any car. Native Apple Music app can in the new Mercedes but most cars don’t have native Apple Music app or Atmos yet. Apple Music
uses a pretty good compression codec, almost as good as Tidal for non-Atmos tracks, you just have to make sure you have that turned on on your phone if you’re using that (Audio Quality under music needs to be set to Lossless and also Lossless for all streaming). Spotify premium is ok, but honestly the car’s high fidelity reveals the inadequacies of lossy compression regular Spotify uses, and I don’t think Premium sounds that good either. USB media files as long as they’re in the correct format sound great.
I do hope Lucid trains all their studio staff to correctly demonstrate SSPro Dolby Atmos in Tidal and explain to customers that to get the most out of it you need to have the right source material. Otherwise most people are going to just play tracks over Bluetooth or CarPlay Spotify regular quality and be underwhelmed. This is not a new issue, it’s been a continuous re-education campaign needed since day 1 the car was released haha.