Thanks to the FS forums, I managed to get a great deal on a mint HD600 for my first over ear headphones, and they arrived today. They're quite interesting... I never knew what a high end full sized headphone was supposed to sound like. Bass impact was actually a bit less than I expected, but I didn't buy them for the bass :evil: These have great imaging, detail, and pretty much play beautifully with every genre of music I have in my collection. My only issue with them is comfort... the headband clamps way too tight and it's hurting my ears. Once the headband loosens up though, I can see these as being my chill out headphones...
Oh and Windsor, I'm using my HD600 with a Yulong D100 (both DAC and amp). I don't have a different reference other than my fuze (which btw drives the hd600s way better than it should), but it sounds pretty good to my ears. The built in amp easily drives the HD600 and I have the volume knob just a few notches above what my IEMs need. At first, I found the midrange a bit thin (neutral on neutral) and I've been going to my midrange-emphasized portable amp for certain female vocal heavy music, but in the end, I found that I could live with the amp in the Yulong and it's lack of colour. If you don't have access to different amps or like your midrange weighty, and must use your HD600, I would avoid the Yulong though. From descriptions, it sounds like the HDP would match the HD600 better.