Hi guys, I'm a long time lurker, first time poster. I just snagged a pair of the 439's and I gotta tell you, I'm not terribly impressed. I have a set of HTF-600s and comparing these two are kind of disappointing. I have a Yamaha RX-567 receiver, and I was playing some tunes through it and comparing both of these headphones, and the Sennheisers started clipping and getting very distorted at high volume, and the HTFs did not at all. Also, these Senns are much quieter. When I have the volume at the same level and just switch between these headphones, the Pannys are louder, and they have much more bass.
I'm hoping that these Senns need to break in a little, I do like the soundstage, and the mids are very crisp, and I hear more details with them than the Pannys, but man, for the price I paid for these Senns, I was hoping they would really be a much better headphone than the Pannys and so far, they are not. One thing about these Senns is that they are really freaking comfy.