Question about audio settings

I am a bit unsure of which sound settings I should set in Infuse and in the Apple TV menu respectively.

Unfortunately, I don’t have a surround system, but the setup is as follows:
OneDrive → Infuse → Apple TV (of course) → LG OLED TV with ARC → Arcam SA30 integrated stereo amplifier.

It is clearly stated in the amplifier’s manual that you must only send a PCM stereo signal, otherwise the amplifier may be damaged.

So my question is which settings would be best. The goal is, of course, to send lossless audio as stereo PCM to the amplifier. The amplifier can handle the bitrate as long as it’s not multichannel.

In Infuse you can choose between Auto, Dolby Digital 5.1 or stereo. I guess DD 5.1 is out of the question because it converts lossless to lossy. What about stereo? Is the multichannel audio (typically DTS HD 5.1) then downmixed to 2.0 but still lossless?

In the Apple TV you can set Audio format to either on or off. On will result in lossy sound, while off will send lossless LPCM. So this must be set to off, obviously.

Regarding the TV’s settings, sound out can be set to either Auto or PCM.

Logically, at least to me, the ideal settings would be:
Infuse: Stereo
Apple TV: Audio format off
TV: Auto

Is this correct? And then I got worried when I read this tread about distorted DTS HD to stereo downmix.

Any recommendations?

On a $3000 amp you would think they could handle anything. They support usb, airplay, and hdmi, all of which could send a multichannel signal which supposedly could damage it?? I guess you would want a preamp or something the handle the mixing to stereo before sending it to the amp.

When using ARC, you should have a few ways to set the audio output. This can either be done in the ATV’s settings, and there should also be an option in your TV’s settings.

The choice will likely come down to which device you want performing the downmix. PCM over ARC is going to be limited to 2ch only. You might try and play with both options and see which sounds better to your ear.

Agreed. It is too stupid if equipment in that price range should be damaged by accidentally sending multi-channel audio.

But this is a very good amplifier for stereo music, including the room correction system Dirac Live. That’s why I have it.

Buying a preamp just to downmix is ​​probably not something I will prioritize.

I did some testing with Apple TV set to Auto/Stereo vs. TV set to Auto/PCM.

Auto on both resulted in no sound from the amplifier (expected since it don’t support multichannel).

Apple TV set to Stereo and TV set to Auto resulted in louder sound than Apple TV set to Auto and TV set to PCM.

I guess this is the same as was found in the tread i linked to, except I can’t say i heard any distortion.