Got my new warranty set today. The serial #s are from a completely different lot. There is a major difference in the flexibility of the headband on my new set. Also the hinges are much smoother and the creaking is completely gone. Overall I fell they have definitely addressed the QC issues in this new lot. If the M4U 1s are similar, no one has any worries.
As for the sound, I am burning the new set in but I have been comparing the old set to some Sennheiser Momentums for a while. Its an interesting comparison because I like the form factor of the Momentums hands down. In doing some critical listening in passive mode driven by my E11, I find the Senns have less overall isolation. I also find that on some songs, its really hard for me to pick a winner but on others the PSBs just are better headphones. The Senns have more bass but its not as tight or does it reach as low. Also the Senns seem to be brighter but they do not resolve as much detail. Overall the PSBs just have a better balance and resolve more detail. With this new set having great QC, this headphone is hard to beat. Considering how good it sounds with the internal amp and also having NC for flights, I think these are a great deal.
Edited by awtryau89 - 11/19/12 at 4:37pm