I have only had my 650s for a few days now, but I can tell they are going to be quite nice indeed. I am still waiting for my Auditor to arrive, but once I have that tasty amp to drive my 650s and 880s, it should be an extremely good little system. I really like what the 650s do for the sound, certainly they colour the music, but everything does to one extent or another. The bass is very powerful I find, espescially considering the 650s are open cans. Now some of the bass is less articulate and may not reveal the finest of nuances that might be squeezed out, however, the engaging presentation and tonal richness of the bass makes for a very rewarding experience. Certainly these aren't designed to be analytical cans, that we all know, but they do what they do so well that I don't find myself wondering about any potential lost detail, I just find myself enjoying the music.
In my experience, very few recordings are so good that you want to have ever last morsel of detail anyway. The treble with the 650 is slightly soft, but not so soft as to rob you of needed information IMO. Again, returning to the music itself, depending on what you are listening to of course, there are often plenty of edges and over-presentation in the higher frequencies and a little downward emphasis is mostly a very good approach. I know there are two schools out there, and the group that want total detail retrieval and neutrality just can't stand cans like the 650s, or at least not enjoy their sound, will always point out the goal should be full portrayl of the original, no added colour. I myself lean that way, but not all of the time, and certainly not to the extent that the wonderful qualities that the 650s possess are lost on me. Everything in audio is a trade-off, nothing comes for free, full on detail can be sterile, cold and stark, too much warmth can be muddy and lose all the timbre and tonal nuances into a warm syrup. But when a good balance is struck, as my initial impressions of the 650s tell me is happening, then you are going to be presented with a rich, and rewarding musical reproduction. People colour music all of the time, in the studio, in performance halls with acoustic treatments and computer modelling of sound dispersion, colouration itself is not always bad. We have various shades of coloured piano sounds, trumpets, guitars, drums etc.. It just depends on how you perceive the colouration, is it positive for you or not?
I started out with the Grado sound (will get some RS1s someday), moved to the Beyerdynamic sound (still there with my 880s that I love) and now I am really enjoying what the 650s do. My next set of cans will likely be the D7000s. As with the 650s, I read many, many thredas about them before deciding I had to have them, and the D7000 sounds like another must try for me. Anyway, so far, as I suspected I would, I love my 650s and can't wait to learn more about them. I will post a review of them and my 880s with the Auditor after I have had a few weeks with them. Cheers.