Amp recommendation for AKG K1000's headphones?

Try one of the new Singlepower Audio Extreme amps that have just come out. There are lots of opions of it with the K1000 on www.head-fi.org. I have owned two amps from them (SDS and SDS-XLR) and they were both much better than any of the other high end headphone amps I had auditioned or owned. Try googleing Singlepower Supra or MPX3 or PPX3 and read some of the reviews of his other amps. The website is not very up to date but the owner Mikhal is very easy to work with if you give him a call.
If your looking for something that will also power speakers. I used the Unison for a while with the K1000 with good results. I also hear the First watt amps are very good with the K1000.

I own the Pass Labs Aleph 3, and it's the best I've heard within $6500. I've only heard so many amps, though; off the top of my head, a couple of McIntosh's newer tube integrateds in that price range, NAD's Master Series integrated, and Ayre's current model.

Burson Audio HA-160

I run my AKG K1000 headphones with a Woo Audio WA5 headphone amp. Great combination.

I really loved the Audiovalve RKV when I used to own K-1000s. They really meshed strengths to create some awesome synergy.

I had a buddy that used to use CJ Premier 12 monos for his K-1000s, but I never heard that particular setup of his... Man, that guy had everything worth having in the headphone world including TWO PAIRS of HE90s!!!