I almost hate to steer this thread back to it's subject heading but I'll give you guys some of my thoughts on the headphones I tried with the Speedball upgraded Crack amp in Chicago.
I really wanted to try some of the better headphones and luckily one of my pals from Co. was just a couple of tables away.
HD800- Really one fantastic match IMHO. Maybe the best the upgraded Crack sounded all weekend. I'd listened to these many times before but was a little underwhelmed with them till CanJam. There were three amps that hit these cans with the "beauty stick" and added just what I thought they needed to really make them sing. One was $10k, the other was a large home brewed amp that would probably cost almost as much to market. Everything sounded fantastic with this pairing.
Beyer T1- I'd also heard these a few time before and from the amps I heard it on, it just isn't my cup of tea. Don't get me wrong, for some folks, these might be a real favorite but even with the juicy, rich tone of the stock Crack, they were still a little to clinical for me.
Audeze LCD-2- These have been a real hit at the last few meets I've attended. Almost as fast and clear as an electrostatic with the mid bass punch of a dynamic, these planar driven headphones would be on my short list if I didn't already have some electrostatics I love. Unfortunately, just like planar speakers, they're a bear to drive. I'm not sure if any OTL will have a prayer of having the oomph to make these sing.
Sony Qualia- Kind of the redheaded stepchild and successor to the famous MDR-R10. These cans were very short lived in the Sony line up but they do have a small following in the unobtainium world. Somewhat like the T1 they are fast and accurate. The upgraded Crack did make them sound better than I recall right off hand, but these detail oriented headphones are way too much cash for what you get IMHO. The only reason I tried them with the Crack is because I take every opportunity to see if I can find that perfect match since they do have a lot of potential.
AKG K501- I've always enjoyed these headphones and actually prefer them to the K701. They are normally quite bass shy but there's something about the Crack amp (and many of Doc's offerings for that matter) that elevates the bass performance like crazy and this is no exception. I just looked them up online and see that they've now been discontinued but the K601 are similar and can easily be found for under $200. Personally, I'd keep an eye out for a used set of 501's which should be a real sleeper at just over $100 (in fact, I might just do that myself).
Sennheisser HD600/650- I'll say right off the bat that I've always preferred the 600 to the 650. With the Crack amp, this is no exception. I've always thought that the 600's were the perfect entry level headphone. You can find them for cheap ( I bought a B stock pair many moons ago before the 650 was introduced for $229 and recently sold them for $125- never did figure out what made them B stock though?).
For real bass heads who demand lots of slam, the 650's could be just your thing. I listen to lots of classical and jazz though so I'm much more detail oriented.
Well, that's about it for the cans I rolled through my rig in Chicago. I'm sorry the selection was a little top heavy but I was primarily interested in headphones I might want to buy in the future.