Over the last few years you've probably noticed more and more people using "studio headphones" out in public, and recently I even saw one brave soul use the open Sennheiser HD 700 headphones in the turbulent bowels of New York's subway. AKG has seemingly picked up on this trend, too, and has added a three-button remote to the existing K550 headphones in the name of portability, resulting in the K551 model.
Design and features
Compared with headphones that are designed for portability like the Bowers and Wilkins P5 -- and in a lesser way the Sennheiser Momentum -- the K551s' hi-fi roots are obvious. These are very large cans and feature enormous, supra-aural earcups. If you choose to wear them outside, you are truly making a statement: "I am an audiophile, and I do not bow to your dictates of fashion." Witness the baby-blue(!) headphone cord and the white color scheme, and when I asked my colleague Jeff Bakalar to score them on a scale of 1 to 10 for potential "douche factor," he rated them as "a hot 7."
However, if you like to be a little more invisible when in public, you might prefer the silver/black version with a black cable. In either color choice, it's a short cable, though -- only 3.6 feet -- and if you want something more suitable for home use you should try the cheaper, hi-fi version of these headphones, the K550s.
The build quality of the K551s is excellent and they feel very sturdy. The swiveling earcups do fold flat for carting them about; no carrying case is supplied. Thanks to the swiveling nature, you might need to adjust the earcups to get a good fit; otherwise you might find an extensive loss of bass response or get some intrusive street noise.