It is not embedded as a core track, but it is bound to it as a TrueHD+DD track. It’s not a TrueHD track with an extra, seperate DD track. But it depends on the player how this is then visualized. Some players don’t show the additional DD track at all and handle it in the GUI as if it was a core track like for DTS-HD. Or it’s listed seperately although it’s not a really seperate track.
But these are technicallities. 
It’s not a core track and that’s what matters.
The DD 5.1 track is not bound to the the main True-HD track in any way, shape or form. It is an entirely separate track specifically mixed for 5.1 playback devices where True-HD cannot be decoded. Truly independent as is required by the Blu-ray and UHD spec. But, yes, just a technicality. As you stated, not a core track within True-HD stream.
Well, we’re going OT here 
Probably not helping users who’d like to get their audio setup running.
Just out of curiosity, what would my options be if I actually picked up an extra pair of speakers and then wanted HD 7.1 audio output? The TV wont pass it through, so ARC is out. Optical doesn’t have the bandwidth to carry it, so that’s out. Plugging the Vero4k+ directly into the AVR with HDMI means I lose 4k video (AVR doesn’t pass it through), so thats out.
So my conclusion from all of that, assuming I understand the technology (please correct me if i’m wrong) is that I would need to buy an HDMI splitter to send video to the TV and audio to the AVR, or upgrade my AVR to one that passes 4k video through?
That would probably work, but to me is a bit of a hack. If you really want a proper 4K/7.1 Atmos etc experience, then I would say that
is the better option.
Have you tested this to be sure? From what I understand, that’s part of the HDMI spec. But we know how manufacturers have the tendency to do what the want 
Yes, i’ve tested it. Unfortunately thats what led me down this rabbit hole in the first place. If I turn on TrueHD or DTS-HD MA Capable Receiver with the Vero4k+ connected to the TV via HDMI, and use ARC to the AVR for audio, I get nothing but silence.
My TV only has HDMI 2.0a, so its never going to pass HD audio natively because that needs HDMI 2.1 as a minimum I believe. So that means other alternatives will be needed when the time to upgrade rolls around.
So your AVR can handle HD 7.1 Atmos? But can’t handle 4K? What AVR do you have?
AVR is https://au.yamaha.com/files/download/other_assets/1/317611/HTR6063_NPB.pdf
TV is https://www.sony.com.au/electronics/support/televisions-projectors-lcd-tvs-android-/kd-65x8500d/specifications
The AVR was bought post-BluRay when HD audio became a thing, but pre-4k video. There were quite a few years in between each technology taking off.
Hmm, that’s a bit odd. I have passthru enabled and ARC. I have a 6 year old Panasonic plasma and a non-4K Denon AVR and it all works just fine. TV is HDMI 1.4. I actually have an AVR X2100W.
ARC doesn’t route all audio through that connection AFAIK. It just allows bi-directional audio so the TV is both an audio source and an output device so it doesn’t matter what your TV supports if the Vero is connected to the AVR. The only issue I could see is the Vero is negotiating with the TV for what it can do rather than the AVR?
As I say my TV is older than yours and my AVR is only the next model on and everything works fine with regards to pass-thru.
His setup explains it very nicely… He can’t route 4K video through his AVR and ARC or S/PDIF can’t route HD audio back to the AVR. If you want both, @Arathen, 4K and HD audio, a splitter or a new AVR are definitely the only possible solutions here. Like @bmillham pointed out already.
Some TVs can handle any audio format and decode it or pass on the core formats. Some don’t. There’s no logic behind it and there’s no specification which requires TVs to be able to pass on certain incoming HDMI audio formats via ARC or S/PDIF. ARC and the S/PDIF-out are mainly made for internal audio from the TV - either from the TV tuners or from apps. The passthrough functionality of audio from other sources like HDMI-in is just an extra.
Sorry there were 90 posts so hadn’t picked up the exact nature. It’s the joy of 4K at the moment. Many UHD BR players have 2 HDMI outputs so you can run 4K video straight to the display and audio to the AVR.
That’s what I meant re ARC, it shouldn’t have any effect on anything 