That would be really interesting.
I'm hesitant to replace Schiit Bifrost 4490 & Asgard 2 for HDVD 800. At first one would say the HDVD 800 should be superior, but the Bifrost 4490 is a superb DAC and it's upgradeable while HDVD800 has a fixed built in DAC with less than stellar reviews, then the Asgard 2 is a clean yet slightly warm SS amplifier, that should be similar to the amp on HDVD800, we all know there's not huge variance among quality SS amps. On top of that, the output impedance is much lower on the Asgard 2 making it a better match for low impedance dynamic headphones.
So yeah... The HDVD800 looks great, and surely pairs well with HD700/HD800/DT880/T1, but Schiit stuff offers plenty of value and versatility.
For instance, the Gungnir MB is regarded among the best DACs out there. Maybe the best for the price and it's upgradable.
Then the Mjolnir 2 can be both Tube and a SS and has really low output impedance unlike the HDVD800.
So the 2k Schiit stack seems to be a no brainer next to the 2k Senn HDVD800.
Except maybe if you have a matching headphone for HDVD800 (say HD800) and appreciate the simplicity, slightly fancier looks, and the Sennheiser blessing.
Thanks for the insight, I'll go demo some of these units at my local retailers and listen for myself.