Several comparisons between CD 3000 and HD 600 have been published on this forum. Most of them have pointed that the CD 3000 soundstage is wider then those of HD 600 and so more suited to reproduce the symphonic orchestra width.
Some of you have discussed of the Leonora overture that sounds congested with HD 600 and wider with CD 3000.
Do one of you have listen to a symphonic orchestra with HD650 ? As the HD650 is considered to be better than the HD600, have you noticed an improvment of the width of the soundstage?

I never heard the CD3000, so i cannot compare to them, but i know that with good triode amp you can have a very nice and wide soundstage with HD-600, maybe not as wide as with CD3000 ( i think angled drivers), but very convincing, you don't feel wearing a phone, you can pinpoint everything on the recording from left to right, and also (but less) from front to back.

Now the HD-650 do that even better, there's a very nice improvement, to my ears ( and with some good direct heated triode ), they simply throw an amazingly precise holophonic soundstage. Marco, i will maybe disappoint you because i didn't really found a much wider stereo image, but what it's impressive it's the way it convey the sense of the original recording location.
You can FEEL the size of the room where the mics are, you can pinpoint everything in a real 3D field...with that quality of soundstage, IMO, you don't need or want anything more. ( I mean more wider, because there's really more about HD-650, the amazing tonal quality, the KILLER midrange...etc )

Headphones with angled drivers will tend to have a wider soundstage. I don't think a smaller soundstage necessarily means congestion. If the amp and source is not very detailed or "slow", things can become congested when everything sounds all mushed together. I don't think there's much difference in the soundstage of HD600 and HD650.

I think K1000 has the largest soundstage but if your source and amp can't keep up, the sound will seem "broken".