Yes, I’ve noticed multichannel LPCM audio is quieter on my (older) PlayStation, so I tend to use Bitstream instead. The thing is, multichannel LPCM audio on Apple TV (to my ears) is approximately the same volume as it’s other audio codec options when played on the Beam gen2 and the Sonos Arc aswell, which makes me think that this issue might be down to the Sony PlayStation, rather than the Sonos Arc, but I do not have another brand of TV HT Receiver setup here to A/B test the sound levels of the PlayStation multichannel LPCM audio compared to to its Bitstream output. If it happens on other ‘Receivers’ then it’s something Sony would perhaps need to address.

That's interesting to hear about the Apple TV. Could well be the Playstation in that case. I'm assuming me thinking the sound isn't as full as the Dolby is down to the volume level. I mean LPCM should be giving me uncompressed 5.1. The Sonos app is confirming this with 'Multichannel PCM 5.1'.

Just updating this topic:

The Beam has just received an update that enables DTS encoding.

Just to clarify the original issue for anyone reading this. On my setup above with a PS5, Linear PCM was too quiet and lacked fullness to my ear (despite it being lossless quality). The Dolby and DTS settings were much fuller and the surround audio was more prominent. These settings resulted in a short but noticeable audio delay however.

After the update, the DTS option now has no noticeable audio delay. I've tested this with Spiderman Miles Morales, and the controller web sounds are in sync with what's coming out of the Beam. Also, dialogue is matching with mouth movements.