Apple TV 4K mixing 5.1 surround channels into the front speakers

I’ve been having a weird issue with 5.1 audio on my Apple TV 4K (3rd gen, A2843) for quite a long time now. I first noticed it around tvOS 18, and it’s still happening after all the updates, including tvOS 26 and 27.

My setup is Apple TV → Philips 50PUS7303/RU → Samsung HT-5530K 5.1 home theater, connected through HDMI ARC.

The problem is that audio from the center and rear speakers is also coming out of the front left and right speakers. All the speakers play what they’re supposed to, but the front speakers play some extra audio on top of their own channels.

For example, if I play a test sound that’s supposed to come only from the center speaker, I hear it from the center, but also from both front speakers at a lower volume. Same thing with the rear channels: rear left also comes through front left, and rear right through front right.

It doesn’t happen the other way around. Sound meant for front left or front right stays in those speakers. The center and rear speakers aren’t getting any extra audio.

It’s not extremely noticeable when watching something normally, but it’s very obvious with a 5.1 speaker test, and it really shouldn’t be happening.

I’m using the forced Dolby Digital 5.1 setting on Apple TV. I’ve also tried Automatic, and both Multichannel and Multichannel (bypass) on the Philips TV. Nothing changes. Automatic has also been a bit unreliable for me when switching between stereo and surround sound.

The strange part is that I don’t have this problem with anything else connected to the same TV and home theater. The built-in Android TV apps work fine, and I’ve previously tested a PC, PS4 and PS5 through the TV without any channel mixing.

I’ve tried resetting the Apple TV and kept hoping that an update would fix it, but so far nothing has changed.

It almost sounds like part of a stereo downmix is being added to the front left and right channels while the original 5.1 channels are still playing normally. I don’t know if that’s actually what’s happening, but the way the channels are mixed seems to match that.

Has anyone else noticed this? I’m starting to wonder whether it’s a tvOS audio issue or something specific to the way Apple TV handles Dolby Digital through my TV. I’d really like to figure out what’s causing it.