Sonos AMP Intermittent HDMI ARC Choppy Audio Fixed

So you where not using the supplied HDMI cable?

You can try reseating the HDMI cable firmly on both ends and make sure it is fully inserted.
Using a shorter, good-quality HDMI cable often helps with ARC stability.
Also check that HDMI-CEC is enabled on the TV and the AMP.
A full power cycle of the TV and AMP can sometimes clear ARC handshake issues.

Moderator Edit: Post is likely AI-generated

No not using Sonos cable - I would use the supplied cable if it was plenum rated and 50ft long.

Thanks - great suggestions but all tried,  I actually wonder if there a mechanical tolerance issue of the internal PCB mounting and the housing which means the HDMI port on the AMP is right on the edge of the HDMI connector specification.  I’ve tried 4 different cables - all high quality (8k rated),  This is definitely mechanical and not a handshake issue as if I manipulate the connector at the AMP side the problem will go away.

That makes sense. If manipulating the connector consistently changes the behavior, it strongly points to a mechanical tolerance or port alignment issue rather than an ARC or CEC handshake problem.

Given that multiple high-quality cables show the same result, the HDMI port itself or its PCB mounting is likely marginal. In this case, a physical workaround (strain relief, angled adapter) or hardware service may be the only long-term fix.

Thanks for sharing this detail, it’s helpful for others troubleshooting similar ARC issues.

Moderator Edit: Post is likely AI-generated

It isn't that the PCB or port is marginal. It is simply that the opening to plug the cable into is too small for some cables.

Wow - I had no idea this would be an interesting topic for folks.

Update:

1. Problem returned - manipulating the cable solve it - I wedged the cable so that it biased the connector down.  2 days - ok - but expect at some point it’ll come back
2. Had a similar concern to one of the post relies - is it a connector issue?
   1. Tried a different Sonos AMP - same problem - so unlikely to be a broken PCB solder joint inside the AMP.
3. Went back to first AMP - but used Sugru moldable rubber to create support around the connector
   1. This helps a lot - but I can still move the connector and cause some short drop outs - but no longer does it drop for seconds or continuously
4. I also ordered a Sonos HDMI cable - just to prove if it’s third party connector tolerance issue - will update when I receive it.

The long length of your 3rd party cable is probably not ideal due to attenuation. I wonder if ​@caroline-harper can comment, as per the previous helpful comments with their knowledge?

As the problem is 100% repeatable by manipulating the HDMI connector I don’t think this is a length / cable issue.  I’m using exactly the same cable and cable length into Sony and Denon amplifiers for eARC in other locations with the same Samsung TVs with no problems.  I’ve also tried three different cables, passive, active and HDMI over optical with same results.  Heck I’m sending 4k video over the same 8k rated cables without any issues.

If its 100% repeatable by moving connector, then its 100% physical connection issue.

My understanding is HDMI ARC uses different pins on the HDMI spec (pin 14 & 19), so your 4k video is using different pins on the connector than the return audio? A poor physical electrical connection on pins 14 & 19 coupled with increased attenuation due to cable length could be the cause.

One other thought, what I would try, do you have an old Amazon Fire TV or similar? I recall they come with a small male to female HDMI connector, that could be used to see if provides a better physical connection to the AMP with existing cables?

hard to be sure but it appears they are using a hybrid, wire and optical, cable. With the fiber covering much of the distance length shouldn’t matter if under a couple thousand feet.