I've tried a lot of headsets and headphones over the years and I can honestly say the JVC HANC250 are the best. Now I know there are more accurate headphones out there and ones with better noise canceling, or are more comfortable, or have more flashy features, but no other single headphone represents the best mix of features like these do.I bought my first JVC HANC250 back in 2009 and I was immediately surprised at the difference in sound quality they represented. I had tried Bose and Sennheiser headphones before this, but none of those other "high end" headphones showed this level of improvement to sound quality. (Bose QC3 and even the new QC15 were particularly disappointing. Sorry Bose fans...) It's like the first time you hear studio monitors. The difference is undeniable even for the "non-audiophile." And let me take a moment to state that I am not an audiophile. My hearing is decent, but I work with and know many people that have hearing above my own.I can best describe the audio quality as reference levels. The EQ curve is very flat. No crazy heavy bass or piercing highs. It's like a good set of studio monitors. All frequencies are well represented, but no frequency is obviously louder then the others. I call them my reference headphones and it bugs the hell out of my audiophile friends. For what ever reason they assume that any headphone under a grand are trash. I can't hear much of a difference in their studio headphones over these, so I think I will stick with the $100 headphones...The headphones will work unpowered (which is great in a pinch) but the audio quality is severely diminished. It sounds about like a cheap pair of headphones that came for free with your Sony Walkman in 1992. Bad.The noise canceling feature works well. I use it to block noise on planes and in a crowded office space. It's not like you can't hear anything outside the headset though. Everything is just much harder to hear. People's voices sound as if they are in the other room even though they are standing next to you. It's pleasantly peaceful. Like a college library.Battery life is amazing. They say 50 hours and they mean it. When the battery starts to die, the noise cancelling will kickoff when very loud sounds happen around you. Then loud things you are listening to will temporarily stop the powered parts of the headphones. The first time it happened I had forgotten that the headphone was powered (despite turning it "on" every time I used them) and I thought the headphones had started to break. This was after two weeks of solid use. The battery life is outstanding.The earphones are lightweight, but not flimsy-feeling like the Bose headphones. The earpads are soft, comfortable, don't make your face leak, and after a short time, are completely forgotten on your head. (I wear glasses!) After 3.5 years of use I JUST this weekend (12.29.2012) wore out the earpads. Replacements can be bought from JVC.com using part number "J34899-001" and cost $14 each. Worth it.The audio cable is the low point for these headphones. The cable isn't extremely short or anything, but every once in a while you will feel like you could use just one more foot of cable. Luckily the audio cable isn't hardwired into the headphones and you can replace it with a 3.5mm cable. Unfortunately not ANY 3.5mm cable will do. The plug for the cable on the headphones is like an older iPhone, that is to say, it's recessed into the plastic. So the best replacements are iPhone headphone cables. (sometimes called "slim" 3.5mm) It's really hard to find them in black though...I've bought 2 pairs personally and I had the studio that I work for buy me a pair. I used all three pairs nearly non-stop for a combined use-time of about 7 years. None of them have ever broken beyond repair. JVC has made something special here folks. Whenever someone asks me about a good set of headphones I don't even think about it. The JVC HANC250 are the best pair of headphones. Period.