Just spent 10 minutes looking for the HDMI cable requirements, didn’t find them.

Maybe read the stamped info on the Sonos cable and match it?

I’ve had good luck with Monoprice in the past but not bought an eARC cable from them.

I had a setup and bought some expensive HDMI cables and was having issue with glitches in 4K video because I was at 15 ft.  I know that is different than audio, but bought the braided 8K Monoprice cable and the issues went away.  Good luck. 

The same thing happened to me! The Sonos ARC Ultra fixed the problem! I was using Maya Zeskit Premium HDMI Cables. I just bought a Projector so forcefully I will have to go back to Non Atmos HDMI cables 25 ft so I bought Highwings 4K HDMI Cable 20FT, 4K... https://www.amazon.com/dp/B07ZVCKBFL?ref=ppx_pop_mob_ap_share

I believe for Sonos anything that can handle HDMI 1.4 and above is OK - below does not do HDMI-ARC. You don’t need great bandwidth’s because you are transporting sound, not image.

Yeah I really don’t k ow why the cable I used would have suddenly gone “bad” but over a week after swapping it for the Sonos provided cord, I’m convinced it’s something either with the cord or the Ultra itself. 
 

I’ve gone ahead and ordered a few random hdmi cables to try and test various brands, types, speeds, etc. next week. If none of them work I’ll be convinced it’s the Ultra itself and probably try and swap it at Best Buy where I bought it. 

 I think you just want to make sure the HDMI cable is HDMI 2.1.  Mine is a very reasonably priced one from Amazon.  I don’t have the Arc Ultra though so maybe that’s not an answer to your issue.  My setup is Sony TV eARC to Sonos Arc.

Yeah; the cable I was using is 100% an HDMI 2.1 certified cable and was the one causing issues even though it worked with my previous Arc soundbar.

And, yeah, probably overkill getting that many cords to test out, but just want to be sure! Fingers crossed one of them solves the issue so I can get back to just enjoying the Arc Ultra!

I’ve seen counterfeit cables, look like the real brand but are just junk. No good way to avoid that scam aside from using a trusted source.

An update for those who care:

I bought 5 different HDMI cables from Amazon (2 Monoprice, 1 KabelDirect, 1 Fosmon, and 1 Highwings). All were 48 Gbit/s cables that support up to 4k/120hz except for the KabelDirekt which I believe is an 18 Gbit/s cord (although their product page on Amazon is hard to decipher if it’s that or an actual 48 Gbit/s cord).

I tested them all this weekend, and the results were surprising.

• Both of the Monoprice cables didn’t work as expected (gave the same issue as the Monoprice I previously had hooked up in my wall -- Atmos and DD 5.1 would cut out and play a lower audio quality and Apple TV couldn’t output Atmos).
• The Highwings did the same thing
• The KabelDirekt seemed to work perfectly
• The Fosmon also worked as expected, although I’m noticing a few quick low frequency “pops” when certain content switches from say, Stereo to 5.1. It’s not super frequent but I notice it when it happens.

So now, I’m between testing the KabelDirekt more just to ensure the popping doesn’t occur with that but I am just flabbergasted at these results. I expected more consistent results.

I’m curious what all of you would do in my situation: try to exchange the Arc Ultra to see if that’s the issue (I have until January to return to Best Buy and bought Geek Squad protection) or if one of the cords is working as expected (without pops) then just move forward with enjoying the soundbar. 

I do have chords that work flawlessly. Zeskit Maya 8K 2.1 eARC 48 gbits premium hdmi cables trust me!

Thanks for the recommendation. Maybe I’ll try it out; also going to call Sonos support to see if this is expected behavior. Still on the fence if I want to try and exchange the Ultra for a new one from Best Buy.

Trust me! 4 years using these cables for ATV4K, Samsung TV, and Atmos Soundbars! They are the true deal! https://a.co/d/4Zethd0

Well I got one, and while it’s working as intended, I’m still getting small random audio pops from the soundbar when the audio format changes (it’s erratic and hard to replicate, but I caught a recording of what it sounds like here). That pop happened specifically when I was toggling my AppleTV 4k sound mode from Auto to 16-bit and back again (I know to leave it on Auto but this was just a way to capture the sound).

So, still annoying, going to call Sonos support now to see if they suggest I try anything else or exchange my ultra for a new one.

I heard it, I remember those audio pops even with my former JBL 9.1, ATV4K, and Samsung Tv. I am almost certain it is not a Sonos Arc Ultra soundbar defective issue. It has to do with the settings and content, that I do remember. That is why you double check the cables, leave the ATV4K on 4K SDR 60, YCBCR, 4:2:0, Match Dynamic and Frame Rate On. The TV on eARC Auto with Passthrough or some people turn off the eARC (on Samsung tvs mostly) and that solves the problem. Gotta keeo playing with settings 

Yeah I have all the audio settings on the TV set how they recommend it, and same with my AppleTV settings (although I think you’re the first to recommend YCBCR 4:2:0 over 4:4:4…

Sonos support mentioned this is a known issue or rather, an issue they are aware people are experiencing and are working to troubleshoot it, so maybe it’s not just me!

Play with the YCBR 4:2:0 with Match Dynamic and Frame Rate On. Or also try Disabling the Frame Rate option. Sounds crazy but these tests sometimes solve these issues. Also even try 4K SDR 60, RGB High, and only Dynamic Range On. Just un case click on Check HDMI connection in ATV4K