The PK1 did sound unimpressive the first week I had them, but now they are my favorite headphones. I use these much more than my D2000. Not that the PK1 has better SQ, but because they are so comfortable and easy to maneuver in when doing something while music listening. I also prefer the open/airiness of these versus the Denon D2000 closed style. However, I keep my D2000 for when I need a little isolation or for when I am doing some intense listening (doing nothing but listening).
The PK1 and the D2000 seemed to have too much bass when I first got them, but both seem to be MUCH better now. Was it a change due to burn-in, or to me acclimating to the sound? I don't know. Both headphones have somewhere between 300-500 hours burn-in each. I also did the markl mod on my Denon when I first got them and before real burn-in time. After the mod I still felt they had way too much bass. Now after much burn-in I rarely feel that way when listening to them... Perhaps I am a basshead now.
The D2000 has a wider sound stage. The PK1's sound stage is not bad at all though. Its actually really amazing considering how tiny of a headphone it is.
The D2000 is just better SQ all around, except when you consider "airiness" of an open headphone.
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But if I could only keep one of them - I would go with the PK1 for overall value and convenience. It's overall sound quality is good enough to keep me satisfied in most situations unless I am in a noisy environment.
By the way, I do not like using IEMs. They do not feel comfortable, and I dont feel safe in public while not being able to hear my surroundings. I also remember reading one thread recently where someone posted about how their ear canal has permanently become much larger since repeated use of IEMs. <- Weird.
If the PK1s could be priced cheaper - I think they would become like THE initial audiophile recommendation of choice on head-fi (instead of the SR60, PX100, or any KOSS). Also, it would get recommended before these because of sound quality, and because of scalability with amps, and also for the new people who have had only experience with ipod earbuds would probably feel more comfortable with another earbud instead of a different headphone wearing style/format that the other usual suspects listed above bring along with it. And I do not see why the PK1 cannot be priced lower, because it certainly does not seem like an expensive headphone to make... Head-Direct needs to bring back the PK1/minibox-e+ value combo again. I remember they were selling these faster than they could make them.
