The 600ohm is definitely the most refined, but not as bassy (very slightly less bass). The 250ohm has the most bass, and least mids. The 32ohm sounds like the 600ohm, with less refinement, but very, VERY close to the other two, assuming you amp them with as much power as you'd amp the 250ohm. The 32ohm LOVED the E09K.
All three sounded fantastic off the E09K, and all three were within a hair of each other in sound and performance. If you analyze, yes there are slight differences, but to the vast majority, I'm pretty sure they wouldn't be able to tell the difference. Its that close, especially on how the 32ohm sounds like the 600ohm. The 250ohm is more refined than the 32ohm, but it has a stronger bass than both, which is noticeable, though very minor.
As far as the E09K, there is only one headphone jack. The volume knob is dead silent when adjusting volume, which wasn't the case on the E9. The E9's small headphone jack had a very high output impedance which sounded noticeably worse than the big jack. They did it to make IEMs have enough volume to play with, but it was detrimental to sound quality. Long story short, don't ever use the small jack on the E9.
Edited by Mad Lust Envy - 10/17/12 at 9:33pm