Vero 4k+ DTS-MA 5.1 audio upscaled to 7.1 by default?

There is a guide to cover how to configure the audio which you can read here…

What your likely wanting to do is turn on passthrough audio so your AVR is getting the soundtrack directly instead of Kodi decoding it and outputting it to an LPCM stream.

Also are you sure that Kodi is actually remixing a 5.1 to 7.1 as I don’t think that is something it can actually do. Perhaps you have your AVR set such that it is using DTS Neural:X, DTS Virtual:X, one of the Dolby formats that act similar when it sees a Multichannel PCM signal come in.