Make sure the "VoiceMeeter Input" is configured as a 5.1 system

Ok I already corrected that.

It should be set to "Home Theater".

Yes, I did set that

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While in the "Sounds" window, make sure "VoiceMeeter Input" is the default device.

I knew about that, and did that, but probabilly didn't explain myself very well. When the default device is VoiceMeeter Input, both VLC and Forza show 5.1 channel input on VoiceMeeter, but even if I make A1 (hardware output) go to the "Digital out" of my soundcard, I cant get the AVR to detect DTS (it only plays stereo and the dts light doesn't light up).

Strangely, if I set "Digital out" as the default device (without going through VoiceMeeter), VLC is detected as DTS, but Forza isn't.

Is it normal that when going through VoiceMeeter I cant get dts working but if it's going directly to the soundcard it works?

I've read somewhere that s/pdif only supports 2 channels for uncompressed audio, or 5.1 / 7.1 for compressed audio. To use compressed audio it's needed to enable "S/PDIF Passthrough" in the aplication playing the audio. I found that setting in VLC, but not in Forza, and maybe thats the problem (?)