I can’t double-check my piCorePlayer setup with HDMI at the moment because I wound up adding a screen and using an enclosure that blocks the HDMI port. DTS is definitely working on that box through a HiFiBerry Digi+, though.
I’m not exactly a Linux genius myself, but the instructions above really didn’t take much. Unfortunately, they can’t be applied to a Max2Play installation, at least not in any way obvious to me. I included them in the hope that they would make sense to the developers.
To my way of thinking, straight pass-through without any alteration on ANY output should be the default behavio(u)r with exceptions being something users specifically have to set. But I play a lot of DTS material and may be part of a very small minority.
Fooling around with this seems to have completely broken all HDMI output on my Max2Play setup at the moment. Oh well, that box is primarily a server anyway.