Just a note on the Yulong D100 MKII. Managed to get one for Christmas to match up with my Denon D5000. I'm a newbie and have little experience with a lot of amps or amp/dac combos. But I am real satisfied with what I got with the Yulong. Know that I was just upgrading from a Total Bithead...and know that the D5000's are relatively easy to drive. But since I've gotten the Yulong I've also had occasion to hear my Denon's with the Schiit Bifrost plus Asgard and the Fiio E17...in my mind the Yulong is a much better marriage (the Schiit was powerful but everything was crowded and somehow muted...the E17 seemed like a toy).
Most of what I listen to is Spotify Premium through my PC's USB...nothing real high end. I added a Venom 3 power cord and a Wireworld Starlight USB cable to the mix. The definition of the individual instruments in most music has gone from good to stunning with the MKII. Incredible presence and timbre. Soundstage is more three dimensional and wider. Only negative is occasional brightness in the high end on certain songs...but rarely. This combination also tightened up the D5000 bass...but I never thought it was as loose or flabby as a lot of people seem to.
Now the Denon's are only 25 ohm cans. When I tried a friend's Sennheiser 650's on the Yulong it really seemed over-matched....either that or the 650's are the most over-rated headphone out there. The Yulong just couldn't bring it out of the fog.
If you're are looking for a great match for your Denon D5000's...or I imagine the 7000's or 2000's...I'd highly recommend the Yulong D100 MKII. Careful with harder to drive cans though !!!