I've had my HF-2s for a while now, and they're still my favourite headphone. Smooth top end, amazing bass, mids are alive and fun.
I have K1000s, though I'm not sure I'm keeping them. Funding an amp is proving to be a challenge. However, I'm possibly looking for a set of cans that will compliment the HF-2s. I really want to love Sennheiser, but I've found them to be dark, and not fun at all. I want a can that's more reference quality, but still knows how to have fun. This will probably be for listening to female vocals.
I've gone through some Audio Technicas, and while I loved them, they didn't make me wanna boogie :)
Oh yes, I should also add that said cans will be amped by my DNA Sonett.