Given the choice, I think most people, including myself, would rather listen to speakers than k1000s.
K1000s are worth it for me to invest in because circumstances do not allow me to listen to speakers comfortably (i.e. live in apartment).
That being said, with respect to any other headphone I've tried, k1000s are the absolute best
for me! I thought about getting a zana deux/hd600 as a second rig, but canceled it because I don't think I'll ever want to listen to another rig at home besides my k1000s.
And at a certain level, after getting a high end amp like a zanden, air tight, or BAT...I think getting a couple of mods to the k1000 will make much more a significant improvement in sound than changing amps.
Along with getting the k1000s hardwired with an equinox or other cable, I'd suggest to any serious k1000 owner to think about getting the cage mod (partial removal of the cage).
It is a SIGNIFICANT improvement.
I purchased another head-fier's k1000 that already had the equinox hardwire and the cage modded so I've never directly compared to a hardwired k1000 with the cage, but I did listen to Voltron's equinox hardwired k1000 and the cage mod was a significant improvement over that..on par with getting the aftermarket cable itself.
I was somewhat unsure, given the diaphram is sitting right next to the ear, but there's a significant improvement in soundstage and bass. Bass goes lower and you start to feel it...like you would with listening to speakers.
The negatives are that lint tends to collect on it so xtra care must be taken to make sure it's covered when not in use. Not sure if there's a safe way to remove the lint, but I'm not sure I want to try to clean it and damage anything. There doesn't seem to be any affect on sound from the lint.
Also, I have a stock k1000 just in case as a backup
so this may be for those who do have an xtra pair and want to experiment a little.