older Denon Receiver with ATMOS
If the receiver supports Atmos, then it is not that old. Did you check if the firmware is up-to-date? Especially the earlier generations have seen fixes and added features through firmware updates.
The multichannel audio decoding not work at all. Sometimes, I get the center channel on the right speaker or I get very loud distortion from all speaker.
When does this happen? With content from where? Through which app?
If it is from reputable online streaming services, then it certainly shouldn’t happen, and you would be right to seek assistance to solve this.
If it is from local files, extracted by you or someone else, or less reputable IPTV services, then file errors or incompatibilities or conversion errors, are more likely.
If it happens with specific apps only, then please name those apps, so that we can concentrate on the same thing.
If the audio system can handle PCM Multichannel at all, then it should work correctly, or else throw an “unsupported format” message. PCM Multichannel is not a complicated system. It works correctly, or not at all when not supported. Wrong speaker channels or distortions are not inherent to PCM Multichannel.
I want audio passthrough or must throw this thing away.
At one point, long ago, passthrough was available, and then it got disabled very purposefully, even for third party apps. I don’t think it is going to change anytime soon.
… DD 2.0 to 5.1, which destroys Dolby Surround options on my AV-Receiver.
That is admittedly a real issue, if you have such wants and needs and also such sources. Pro Logic is not supported, nor is computational upmixing of clean stereo tracks. That being said, if your source has stereo audio, then the surround sound experience was not a priority for the producers, or not of that time. GIGO.
