Reposting this in the hopes that I now have enough karma!
Hey y'all. I've recently purchased a Sony HT-A5000 soundbar for use with my Sony X90K tv and Apple TV 4K (2022). I've had the X90K for just about a year and the ATV4K since February of this year (9 months at the time of writing). I purchased the HT-A500 in the hopes that, at a later date, when I buy a PS5 (or if I want to bring my Series X to the living room) I would be able to connect the ATV to the soundbar, which would be connected to the eARC/HDMI 2.1 port (HDMI input 3), thus freeing up the other HDMI 2.1 port (HDMI input 4) for the console and allowing the soundbar to receive an audio signal from any devices connected to the X90K.
However, I've not been able to get this arrangement to work consistently. Whenever I pass a signal through the soundbar from the ATV, the screen goes black for about 3-5 seconds, with intermittent flashes of video content (i.e., the home screen, settings app, etc.) preceded sometimes by a millisecond of static or green/pink, lasting probably 0.5-1 seconds each, continuing ad infinitum. Using the same ultra high-speed HDMI (48 Gbps) cables, I've connected my Macbook Pro and my Xbox Series X and managed to pass perfect video signals through the HT-A5000 to the X90K, with audio from the soundbar. I've also connected the ATV directly to HDMI input 4 using the various HDMI cables mentioned above and have run the HDMI cable test via the ATV's settings—each time the cable was able to pass a high bandwidth signal. (Note: all devices are updated to their respective latest OS or firmware.). Connecting the ATV to HDMI input 4 and connecting the soundbar to the eARC/HDMI 2.1 port (HDMI input 3)—i.e., no passthrough—works totally fine.
I initially thought this was an issue with having the ATV set to output 4K Dolby Vision, so I changed the video settings to 4K SDR, with range and rate matching on, which worked fine for the ATV home screen and in apps, but as soon as I switched to Dolby Vision content (Dune on Netflix), the issue returned and nothing I tried remedied the issue. I've tried changing the HDMI settings on the soundbar to Enhanced (4K @ 60 Hz) or standard rather than Enhanced 4K @ 120 Hz/8K @ 60 Hz and I've tried various external input settings at the TV (Standard, Enhanced, Enhanced Dolby Vision), but to no avail. I've also tried turning off CEC at the soundbar level and turning off home theatre control on the ATV, but neither has helped.
Here's the kicker: I've also purchased a JBL Bar 500, which supports 4K passthrough @ 4:4:4 and 60 Hz with Dolby Vision and have tried using passthrough from the ATV to the X90K. While the video doesn't flicker, there appears to be some degree of signal degradation, where the colour and sharpness are affected, leading me to believe this is an issue with the ATV.
I was wondering if anyone has had a similar issue and how you managed to resolve it.
TL;DR: Setup is currently Apple TV -> Sony HT-A5000 <-> Sony X90K, but HDMI video passthrough does not seem to work. Soundbar clearly is registering that audio is from "HDMI in" and playing audio correctly. Video flashes/flickers in between periods of entirely black screens. Please help!
