I the pre- version, so the HD-AVP, combined with the K-38.
It is a very powerful combination.
Yes, the manual is just skimming the surface and does not provide all the information.
Other problem is that the mains out are switched between the USB outs, and the multidac outs.
But I use both combination, with JRiver. That allows me to switch zones and settings between 2-channel and HT.
As a USB DAC for 2-channel music, it is very nice, but has no volume control, so, you'll have to do that in software, or add a pre-amp.
It is also a very capable machine for HT duty.
I use the HDMI out of the computer when watching movies. It then becomes a 5.1 good little setup, with XO management and EQ on all channels.
It can actually become a 5.3, because it has a pair of mix outputs R and L, so one could add a pair of stereo subs to it, providing you also have passive XO in those boxes.
Complexity arises when dealing with the settings. There's no information about the different formats available and how they affect the whole system. It's mostly trials and errors, until you get it right.
It's a little quirky, but quite a powerful machine.
Unfortunately, it won't be part of the line up anymore, so I don't know about support in the future.
Yes the HD series has been a challenge due to the initial platform, and design goals.
And you are correct that the manual is not as expansive as some.
But that is the extent of the documentation with the exception of a few posts and threads here on AC.
You might also find the additional info HERE in the FAQ section under HT.
I think the units, which are on "close out" should best be viewed as a 2 channel Pre or Integrated, rather than a SOTA Multichannel solution.
The ESS SABRE Dac chipset is directly accessed via the USB input.
While the other digital inputs may also go through the 2 channel DAC, the circuitry is different and runs through a more extensive process to add Bass Management, Equalization, and Multichannel Processing.
So the PUREST Stereo Path is the USB. It is not "quite" an IDA-16 but quite close when used this way, still making it a great unit under those circumstances.