I've been considering this amp as it's basically the only one in my price range I'm able to buy in Shanghai. From an actual shopfront that is, I know there's the Tianyuan Zero and the Yuezhibang Musiland 02, both of which seem very popular on head-fi, but I can't seem to find a shop that stocks them.
So I had an extended listen to the Yulong today using just its DAC. Setup was:
ALAC -> USB -> Yulong -> Graham Slee Solo SRGII -> HD650
The Solo's two inputs proved pretty convenient for AB'ing as I compared the Yulong to the iPod.
Now these are just a headphone noob's impressions so take them with a grain of salt, and the Yulong is only the second DAC I have ever heard. The other was another Chinese DAC, the Arce MDAC which no one seems to have heard of so I won't go into it.
To my ears the difference between the Yulong and my iPod are very subtle. The main things I noticed were that the Yulong seemed to produce a slightly cleaner and more articulate sound, and, depending on the recording, some instruments sound a bit farther away from my head than they do on the iPod. So I guess it has a wider soundstage.
My overall impressions were very positive, though to be honest if I was getting the same audio quality as my iPod but out of my computer I probably would not spend the $250 to upgrade to the Yulong, but money is tight so that's just me. Since my iPod has very limited storage and I'm hoping to use my computer as my main source I am quite seriously considering buying it. Note that my impressions were also from the USB input, I understand coax and optical may result in slightly higher sound quality.
Also to those who are looking for only a DAC and are put off by the cost that goes into the wasted amp, I was told by the guy at the store (who has always been very candid and helpful) that the amp only adds 200 yuan (~$30) to the cost of the unit.