Extremely comfortable with well balanced, neutral soundWorking in a cubicle, I listen to music nearly all day, every day. I have been using the AKG k601s for the last fourteen months or so, plugged into the headphone jack of a component size CD player. I listen to a wide variety of music including electronic, classical, and post-rock.
COMFORT.
With this experience, I can confidently report these are the most comfortable headphones I have ever worn. The are very light on your head, and apply most of their pressure to the area around your ears. The soft, well padded cups fit entirely over my average sized ears, with room to spare--even with eyeglasses. The leather headband pressed on the top of my head a little when new, but that slight discomfort disappeared quickly. Again, I cannot think of a better testament to the comfort of these cans than the fact that I repeatedly wear them for four- or five-hour stretches. I also own a pair of Sennheiser HD595 headphones that I can compare the k601s with. The Sennheisers also are very comfortable, but the ear cups are not as large, and may present problems for folks with larger than average ears.
SOUND.
I have been very pleased with the sound of the k601s. When I first got them, I immediately rediscovered my CD collection, hearing details and nuances I had never noticed before. I'm not talking about a minor difference, but an incredible, eye-popping experience. If you have never heard high-end headphones before, you will hear songs like you've never them before. This is my favorite aspect of the k601s. Whenever I buy a recording now, I always prefer to hear it first over these headphones, rather than my home system. As far as neutrality, I believe they are fairly uncolored. I have not seen anything from AKG, but an impressive response curve can be viewed on www.headphone.com, which, by the way, is a great merchant. Since the drivers are so close to the listener's ears, headphones typically have reduced output in the higher frequencies (i.e. treble) and higher output in the lower frequencies (i.e. bass). The curve for the k601 follows this philosophy, and to my ears, the cans sound fairly balanced across the frequency range. The bass may be a little thin, though the notes are reproduced and audible--just not with large amounts of sound pressure. Again compared with the Sennheiser HD595s that I recently acquired for home listening, the k601s have a noticeably diminished lower frequency output. I'm not sure how I feel about that, perhaps because I have become accustomed to the leaner k601s, and the Sennheisers bass seems more prominent than its higher frequencies. Many folks recommend a long break-in period for the k601s, and I suspect it has to do with getting used to the bass output. They are not heavy hitters as far as bass goes, so hip hop fans probably will be disappointed. I don't know, but suspect--based on reviews and the response curves--that the bass output is one area in which an upgrade to the top-of-the-line k701s would be justified.
DURABILITY.
Using the k601s every day in an office setting has exposed them to a fair degree of wear and tear. I have found them to be very durable, even after repeatedly dropping them onto the floor and running over the cord with my chair. The ear pads have come off, but they just click back on. I returned the cans for warranty service after I started hearing distortion: where the cord connects to the left side had become audible loose, though not visually. This was probably because of misuse on my part (allowing the cord to get caught and having it pull taught on the earpiece at times), but AKG re-corded the headphones for free. The cord itself is fairly thick and well insulated. It has withstood numerous roll-overs.
FUNCTIONALITY.
The headphones have an average impedance overall, less efficient than smaller supra-aura `phones, and less efficient than other circum-aura, open-backed cans like the Seenheiser HD-650s. You will not necessarily need a dedicated headphone amplifier with the k601s. The headphone jack on my Marantz CD5001 cd player drives them very well. I also have had success listening to internet radio, plugging the k601s directly into my desktop computer. I suspect, though, that an Ipod would not have enough voltage to drive these very well, and I doubt you'd want to wear the bulky k601s on the subway or bus. The unique design of these headphones may or may not strike your fancy, but it achieves comfort, as I've already described. I purchased a pair of HD595s, however, for home use because the k601s aren't as suitable for wearing while laying on the couch with your head on a pillow. I must also mention that I use these open-backed headphones in an office setting. Even though they are not a sealed design, I've found that very little sound leaks out at the volumes I listen to. I've confirmed this with my co-workers in the adjoining cubicles. Plus, I like being able to hear my telephone ring or know when someone has entered my cube. If active noise reduction is more important, however, you'll have to look elsewhere.
CONCLUSION.
At from two to three hundred dollars, the AKG k601s are top notch headphones from a well respected, science-based manufacturer with enormous R&D resources. I cannot imagine you will be disappointed with them after an extended listen, except perhaps if you value bass reproduction over everything else.
