3-d sounding headphones.....

First, you may want to check out headfi.com for the best feedback and recommendations on cans. Second, I just got some JVC Victor 1000s that are great, but for a lot of money ($1,000 new and only avail. in Japan) but there is/was a used pair here for $500. Not your typical "JVC" stuff, but real good cans. Third, what are you listening to them through? A good headphone amp can make all the difference.

If I understand your question, there are two factors coming into play. First is the recording. Binaural recordings may help the imaging, or other recordings where the microphones were set up specifically for headphone or earphone playback. The other factor, for ordinary stereo recordings, concerns the geometry of headphones and where the sound is coming from, that is, the drivers are directly aiming into the ear from the sides. There might be some headphones out there that address this by putting the drivers in front of the ears, but I'm not aware of any, and they'd probably be very bulky. Until you get the sound coming from the front (or a recording made to replicate the how your ears pickup sound from the sides), you're going to have headphone imaging.

Ultrasones are incredible in this regard.

I don't know what you mean by dimension. If that means depth and width...you're not going to get that with earphones. You will get much better clarity, evenness of sound and lots of drawdroppingly good stuff from earphones, but the naturlness of speakers, and real instruments in real space can not be had. I agree with CKoffend. No one knows as much about headphones as do they. Just reading their website is interesting and factual.

Grado GS1000s have a big, open sound with lots of depth.