I don’t have experience with DTSHD encoding, because the suite never did anything but freeze up when I tried to use it.

But I do have experience with Premiere exporting things with massive gain reduction for whatever reason. The issue, as far as I could tell, seemed to always be with what it was importing. Even though they were perfectly fine wav/mp3/ac3 files, its import function seems to be bugged. I fixed it by simply taking whatever source I was using, importing it into audacity, exporting again as wav, and then bringing into Premiere. I could then compare it directly to the previous, bugged import and see directly that the peaks were higher. And that carried over into what I exported from Premiere, now correct.

I don’t know if this is the same problem that you’re having with DTSHD. I assume that you know how to export the lossless audio from it and not just the lossy core (I’m not sure that I know how to do that). You say ‘demux’, but I don’t know if that means losslessly re-encode in this context. In any case, you could try re-encoding the wav audio and importing that into Premiere. Perhaps you will luck out.

Edit: Reading over in the other thread, it seems even less likely that this is the same problem, as you don’t actually notice the drop when looking at the directly exported Premiere audio. It only shows up after the next step.