Ta for the recommendations. Got my k501's today. They sound great to me un amped (though im no audiophile), but on one classical guitar songs I had on it had problems with some small parts of it. I guess that's where the amp comes in?

I tried them out with a film as well, whilst watching Das Boot I was particularly impressed with the sound of the water gushing into the submarine.
Have I heard little of what the k501 can do though?
I have had a look at some of the recommendations thus far:
Yarland P100 - £220

far too expensive for me.
perreaux sxh1 - £200 on ebay
01 amp/dac =
this one?. Not sure how much it is but I cant find any on the net for sale.
Musical Fidelity X-Can V2 - Are a lot closer to my budget, they all tend to sell for around £110-120.
Little Dot Micro Tube - Also viable at around £130 from China.
The little dot Mk 2 tends to go for around £100. Would prefer an amp without those things sat on top though (what are they?). I would only end up knocking them off my desk and breaking them.
Since I use my headphones solely on my pc through my x-fi music card, isn't there one particularly for use with pc's? What do you all think of
this usb one?