On the other hand, I was VERY impressed by the Mad Dog headphones by MrSpeakers (modified Fostex T50-RP). For the price ($300), I thought they were a truly phenomenal headphone. When compared back-to-back with the Thunderpants, I found them to be much more even-keel and neutral across the spectrum, while still remaining quite detailed and clear for a closed-back headphone. The Thunderpants headphones, by contrast, struck me as being much more of a basshead headphone, curiously enough, which I wasn't expecting at all. Dan Clark (Mr. Speakers) was also very generous with his time in explaining the measurements he took as far as trying to improve resolution and soundstaging as compared to the stock T50-RP. He is an electrical engineer that has worked in audio for quite some time, and he obviously knows his stuff. The headphones should probably be used with an amp to sound their best, though, even though they have a very low 50ohm impedance rating, and could potentially be driven directly off an i-pod.
I cannot express how much I agree with this. I set up my stuff on the next table over from Dan, and as such was talking to him and was one of the first people who sat down and listened to his headphones. He practically forced them on me. And I was floored when he told me the price to the point of speechlessness. All I could say was "that is a very good price." He really nailed it for his price point. I spent a considerable amount of time talking to him in the beginning of the show about various things. He is a great guy and knows his stuff. He was always ready to explain everything. I actually spent more time talking to him in the first hour than I did listening to gear. I don't regret it at all. They may very well be my next "Portable" pair when I get my O2 built.