It should "work" but I don't know what the sound would be like with 600 ohms impedance. I have a feeling that those arn't too common, the 25-II's are the ones most people seem to go for. Do you have a pair?
Don't let the big bad 600ohms bother you.............they do just great with a typical setup of an iPod (mine iModded), a typical amp such as from Xin (which is what I choose to use), or Ray Samuels - and you're just fine. They are not at all tough to run. I have a pair of HME25 modded, and a new pair of HD25-13. Both are really the same thing and better IMO than HD25-1. They provide a little smoother treble, and bass that has more authority. My personal preference is to use the velour earpads, and also cut my cables to 1 1/2m/miniplug for portable use.
I don't think he wants to use an amp, there was a post about this not too long ago, I think it said something like they will work fine but you have to turn the volume up a few notches higher. You may want to do a search to find it.