An ETA on LPCM would be nice. Having similar problem because I have Apple 4K as well. 

Sonos, as a rule, doesn’t give ETAs for software updates. 

Sonos barely ever announces they are working on something like this, never mind give an ETA.  I'm afraid you're just going to have to be patient.

Apologies for jumping onto this thread but my ? Is related to LPCM / ATV4k as well. 
 

I have a 2016 Samsung 60" KS8001 Smart 4K SUHD TV with an Apple TV 4K. 
 

There is no eARC but ARC, accepted there is no ATMOS for me for now till I replace my TV but I want to ensure I am getting the optimal 5.1 experience. 
 

I had a Denon 5.1 wired setup previously and know that due to the speakers I would have experienced surrounding sound more so than with ARC. 

The ATV4k has default settings Audio settings and the ARC sounds great so for streaming apps pushing out 5.1 can I expect the ARC to output the same as well or must I be waiting for the LPCM software upgrade? 

If you have an Arc, sub and surrounds then you will get excellent DD5.1 providing your TV passes it via ARC or you run optical into the Arc using the provided adapter from the TV optical (If the TV can pass it) or a hdmi audio extractor. 
 

Coming back to the LG conversation; I held off upgrading my C9 to the 3.80 firmware for this very reason. The TVs passthrough for LPCM is of no use to me until Sonos upgrade the Arc in the future. My other option would have been to use the internal TV apps for 5.1 content but I’d rather run the old firmware for a bit longer and save myself the hassle of constantly switching the audio on the ATV. Let’s hope this software upgrade for the Arc will come sooner rather than later. 

I have the same issue with my LG B9 and my Apple TV with the Arc. Hopefully Sonos will add this soon. It’s disturbing that such an expensive soundbar doesn’t support LPCM out of the box. 

Even more disappointing that Apple doesn’t support Dolby Digital Plus from their apps. 

FYI, Apple TV 4K outputs in Dolby MAT 2.0... 

Which requires an eARC connection. 

so whats the problem then?

Sorry, what is what problem? I don’t see a post from you in this thread indicating an issue. My response was to Downl1nk_1’s comment about the Apple TV’s output. 

my tv has EARC which is connected to the Sonos Arc but the ATV only works with 5.1 as soon as I try to play an atmos format movie there is zero sound on Sonos Arc when Atmos is enabled on the ATV. I have the LG set to passthru. Hoping that Sonos update the arc to accept LPCM as soon as possible otherwise I spent $3000 for a new soundbart and tv for no reason. My LG appletv app doesn't play Atmos as its not supported yet by LG but hopefully will when update , the only app that seems to work for me is Netflix on LG tv.

Needs to happen soon. It’s a joke that I’m having to use stereo on an 800 quid sound bar

Would like to second this, I’m in the same situation. I have two devices (LG C9 and an Apple TV 4K) that as I understand it are following home theatre best practices in passing through multi PCM and one device (the Arc) that is holding everything back - I could tolerate it when it was just my Switch affected by Sonos’ lack of multi PCM support, but with the Apple TV also caught up in this the Arc simply isn’t worth the money. Based on what other Sonos owners have told me about their struggles with DTS support, I’m planning on returning the Arc if an ETA for multi PCM isn’t confirmed before the return period lapses. Will just switch back to my old Playbar and put aside the cash to migrate away from Sonos.

Do people come on here as a way of passing time, for reasons other than to talk about Sonos products? Must have such fun lives.

What about a LG CX owner and apple tv 4k, would I get same issue reported on here, was going to order but looks like Im best holding off for now.

I also own an oppo203 but gather that would be ok.

No, some people come on here to launch silly threats demanding a completely unrealistic response time for their pet feature to be implemented. 

@jgatie A threat requires leverage...I don’t think my one Arc return is that much leverage against a business the size of Sonos. So relax. Now can you leave us alone to talk about this issue? Thanks.

@ledzep1: based on this thread it looks like a similar firmware update has been/will soon be delivered for the CX as well. So my suggestion is hold off updating to the latest firmware if you’re planning on getting the Arc, or hold off getting the Arc until Sonos have delivered LPCM.

I mean is it a certain Sonos will fix this in an update, if yes I don't mind placing an order and in the meantime hold off updating my TV.

From what I gather the issue is when playing Netflix 5.1 audio and it gets output as stereo 2.0 

Would this issue happen on my oppo203 as well?

Really a basic operation of the Sonos is NOT a pet feature it is something that should have been a basic mode of operation is a sound bart thats cost $800. Granted maybe appletv needs to also modify how they send out their signals but from what I have read they are not alone.  I have spent $3000 but a new tv with EARC and a Soundbar to find out that all my movies on ATV will not work with Sonos because they didn't include thew ability to accept LPCM format. Not good enough! 

Oh, so then it is an idle threat?  I beleive that makes my point.  

@ledzep1 Unsure re: the oppo, I’m having to learn a lot of this stuff afresh because it’s been a long time since I got my Playbar and things have changed a lot since then. The issue you describe is accurate (not just netflix, it also affects other Apple TV apps, eg HBO Max) but you should note it only seems to affect people who use the Apple TV 4K as a source. I’ve heard it doesn’t affect those who stream from the LG TV’s own WebOS apps (I’ve yet to verify this myself).

Regarding whether or not Sonos will update the Arc, they’ve said that they will within another thread here. But I wouldn’t call that official confirmation and (as many people here will remind you) they’re not in the habit of providing timelines. Personally I wouldn’t consider the feature confirmed until they’ve shipped the update, so as things stand I’d advise you to make your purchasing decision assuming that the Arc will never get multi PCM support.

@jgatie It makes it a description of my planned course of action. But since you seem to want your point made, consider it done. I cede to your mighty point! Now there must be another thread somewhere that’s ripe for your conquest. Surely.

The amazon prime and Netflix apps on my lg work fine with the arc, however their appletv app does not support atmos at this time but they state it will in a future update. So the only problem with atmos is when using the ATV to send the signal (MAT) and all of their apps only work up to 5.1 but not atmos as Sonos Arc doesn't accept LPCM