Dear Kal (@mitr),
You are absolutely right - this is impossible to achieve in Roon right now. You have to choose : either get the 5.0 files, or the 5.1 files to play nice.
In my opinion, there must either be a bug in Roon’s channel re-mapping, or something’s missing there. If so, then this post should simplify the way to reproduce.
My situation slightly differs from yours : I have no output on my physical center. You have no output on physical rear right. I believe this may be explained, by the way this bug ‘confuses’ the user (or perhaps me).
My findings are still not ‘final’, but I’ll share what I observe so far. Perhaps you (Kal) can confirm if you can replicate what I saw.
I would also kindly like to ask @support, if they can doublecheck this.
My opinion is, that it goes wrong when Roon tries to apply channel mapping from 5.0 input, to 5.1 output.
In case it matters : this is ROCK. HDMI output set up with 5.1 layout. Feeding an Anthem processor over HDMI.
When I take a 5.1 source file, I get the following result. A short way to describe : all is correct :
Roon channel -> Physical channel that is mapped to :
Left front -> Left front
Right front -> Right front
Center -> Center
LFE -> Subwoofer
Back left -> Back Left
Back right -> Back right
However when I take a 5.0 file, Roon wants to (obviously) re-map it to 5.1, and things get mangled up:
Roon channel -> Physical channel that is mapped to :
Left front -> Left front
Right front -> Right front
Center -> Subwoofer
LFE -> Back left
Back left -> Back right
Back right -> (unable to determine, as I have no more physical channels)
It’s as if they’re skipping the center channel in the chronological list-of-channels, instead of skipping the LFE channel, when re-mapping 5.0 to 5.1.
One nasty thing is : I’m pretty sure there is no universally accepted ‘standard’, that describes how to perform such a remapping.
So this could be quite a challenge for Roon… On the other hand : the way that they’re doing it NOW, is not a known standard to me.