I couldn't find a discussion thread for these surprising little cans so I thought I'd make one. First, some photography:
Owners of the popular dt 1350 will notice a few key differences. Firstly, the headband has been completely redesigned - it's a little bit wider across and bulges near the top. The new headband reduces the clamping force that many found unbearable on the dt 1350. The new headband combined with the new ear pads (which are also available on later model dt 1350's) makes for an extremely comfortable headphone. It isolates and makes just as good a seal as the dt 1350 does, but has a wider "sweet spot" and remains comfortable even if you're wearing glasses. The T51p also has a y cable that terminates in a 90 degree 1/8" connector - perfect for on-the-go.
I'll write more about the sound when I've put more miles on them, but my first impressions are very positive. They somehow maintain the clarity and detail of the dt 1350 while adding a very impressive bass response. It reminds me of the bass on the dt 770 but more taut and well-defined. I will also say that the bass digs deeper than I expected, and the sub-bass can be palpable at times. All this low-end emphasis definitely gives this headphone a warmer feel than most Beyerdynamic headphones. It makes my Beyerdynamic T90 seem extremely bright. However, there is still enough sparkle and detail in the treble to remind you that you're listening to a pair of Beyers.
I hope there's at least a few of you out there who own and are enjoying these headphones! I'm surprised how little attention they're getting on head-fi.
Edited by DangerToast - 1/30/14 at 7:44pm