not the HD-600s, but Stereo Exchange on Broadway near where the old Tower Records was, has the HD-800s in a display case as you walk past the cashiers area (top shelf, small glass case). I was going to ask to try them on, but after 10-15 minutes of not being able to the attention of a sales-person, my friend and I walked out and took the loss. We stood near the giant TV in the front of the store, and my friend even sat in the chair in the middle of the room for 1/2 of the time. We even watched as one sales clerk leaned on the glass next to the cashiers table (15 feet from us) talking to some other guy about what seemed personal joking around things (my opinion)
BTW: This was Monday around 3pm.
On one hand though, they would have top of the line sources to test on. I didn't see the HD-600s, but they may have them also.
This store used to be the place to go in NYC (I remember when the back rooms had all the used McIntosh gear and there were lines to get into the store. I once bought some B&W speakers from this place. But I've been in the store twice in the last year, one time they had a 'Glee' promotion going on (UGH) (Piano and cheerleaders in the front of the store) and on Monday where there were maybe 5 people in the store, and I could not get a sales clerk.
My friend's comments were, "Guess you have to buy high end electronics on line now." & "Guess we will never be going back there again"