Here are my belated comments on the meet:
Some time ago I listened to a bunch of Alex’s headphones and thought the HE90 was a clear standout. I heard nothing at the meet to make me change my mind. I also still don’t care for the sound of the Qualia.
The AT DHA3000 was a very nice sounding amp/DAC, although I didn’t hear an A/B between it and anything else.
I could not hear the difference between the two HP2 headphones with their different cables. That’s okay with me, since I own the one with the standard cable. Perhaps a quieter atmosphere would have revealed something.
The M³ had great looks and sound. The only comparison I heard was with Xin’s SuperMacro amp. With the 70 ohm HD25-1 phones the bass had better impact on the M³, which isn’t surprising given its big output devices. These phones boost the bass too much for my tastes but it may have made this difference easier to hear. The little SuperMacro was pretty impressive though to stand up to a comparison like this.
I did some amp comparisons with my 40G iPod as a source, using KSC75 and Beyer DT231 phones. I have many sources at home, but this is the one that use more than any other, either at the office or on walks. All of the tracks I listened to were recorded from CDs using Apple Lossless encoding. The first amp I tried was a META42 type circuit portable amp that I had built, driven from the iPod line out, and it clearly bettered the sound directly from the iPod headphone output. The bass was much better, but overall it had a clarity that the iPod lacked in comparison. Then I tried a couple versions of the SuperMacro amp, and the sound improved further still. Lastly I tried the SR71. It was also very good but a little darker sounding than either SuperMacro (the two SuperMacros had different op amps; one had the OPA604 and the other the OPA627 I believe). I preferred the SuperMacro with this setup, and was impressed enough to order one. I did spend quite a bit of time talking with Xin about this amp, and was very impressed with a lot of design details although I tried not to let this color my evaluation. Xin is a really nice person to talk to, and his amps have come a long way from the little plastic cased micro amps with underpowered supplies and funky digital volume controls.
Unfortunately I arrived a bit late, so my time seemed limited. My thanks also go to the meet organizers, and the preprinted name tags were a nice touch. It was nice to see familiar faces as well as new ones.