Received mine. SN 1274. No rattle. Overall, I am enjoying these. Spacious soundstage, and a very smooth sound signature. A really nice pairing to go with my Grado SR325i and Beyerdynamic DT 770 Premiums (600 ohms). The K7xx have easily kicked my AT AD700s to the curb. However, the build quality is just okay. I believe Massdrop/AKG should have made it known that these were going to be made in China and that a few other details of the headphones would be "less" (ex, painted lettering instead of raised lettering). Hard to complain for $200, but when they advertised these as being a Special Edition with improvements, you would (hopefully) assume that there would be no sacrifices as well. But, they do sound great.