I've read quite a lot about these and tried them quite a few times with their demo in shops.
Astonishing noise cancellation.
Issues that have come up with them is the treble being a little curtailed, although I thought they sounded ok. I thought the bass was a bit Beats like too. With noise cancellation off, they're shite. I thought that was a pity. Noise cancellation causes very low level hiss.
I use a Sennheiser PXC450 which is pretty good. In fact, I've just had to replace the pads which was a bit of a joke. Getting them in the first place was a slight challenge. eBay was my friend. They were expensive and a fiddle to get on with a daft plastic retainer. Now they're on, the headphone is fine though. My old ones had degraded and split. They are extremely soft and cushy so that they form the right shape on your head.
I've had the PXC450 for a very long time; since it first came out in fact.
I think it is a better headphone than the Bose really. The sound with noise cancellation on is way more balanced and natural. No fat bass and quite extends in the treble. With noise cancellation off, it also sounds really good. It develops a little more bass with cancellation off, but not over the top.
The cable comes off as well, so it can be used in a variety of situations.
Only thing is that it has a very high impedance with the noise cancellation on. Somewhere in the region of 700 ohms I think, so it does need an amp really. That's where the Bose wins out. Without NC, the impedance is lower. (More bass as a result?) Funny that the difference in volume with NC on or off isn't anything really, which I don't get, since the impedance drops with it off. Maybe sensitivity changes?
I originally bought it for flying. Take the cable off, turn noise cancellation on, and little buzzy planes or helicopters' engines don't smash your ears to pieces. Also no-one can easily talk to you then!!! So you can sleep. It has a switch to hear as well by turning the music down or off if you want and the external mic sends sound into the cups. That is a really useful function and a great use of the noise cancellation microphone.
Noise cancellation works really well in planes and also when the wife has a washing machine or tv on. Even a noisy motor for our power shower gets knocked out with these. It's a big 'un and send the Niagra Falls out so the Senn is really blocking a lot.
If it's just general house noise and I just want a little less attenuation, then I listen without noise cancellation. Rumbling sounds get through but speech outside is muted. If rumbling is a nuisance, then I just switch NC in again. Or else I use the dt770.
That's where the Bose isn't so useful. With NC off, it's really not very good, whereas the Senn still sounds excellent. I think Bose missed a trick there really.
I seem to remember that the Senn cost a lot though and it's no longer available which is a pity, because it is very good. I prefer it to the Bose. Even in the garden with lawn mowers going off in the summer, I can wear them without the wire just to cut it all out if I'm concentrating or reading a book!!
It never really got the attention that it deserved because of its price IMO.
I wish that some electronic genius somewhere could completely knock hiss on the head though with all noise cancellation headphones. Never heard one that doesn't hiss, although both the Bose and Sennheiser aren't bad in comparison to some others that I've tried. In noisy conditions, the hiss doesn't intrude, but in the front room with say, TV, it can if you are listening ultra low in volume to speech. It's not a bad noise though thank goodness, but it can kick my ocd nature off.
If it does though, I switch the NC off and use it as a standard closed headphone since the sound is still very good.
For anyone wanting a cheap but good sounding noise cancellation headphone, I also had a Goldring one once which really was quite good. It hissed a little bit more than the Senn but then again, the Senn was a lot more than this one. It's comfortable with great sound, although I think it might be a bit delicate and has to be treated with care because of the plastic use. I didn't have trouble with mine, but some people reported plastic cracking. Great for holidays or travelling.
Not as good with NC off, like the Bose though. Best to use it with NC on.
www.amazon.co.uk/gp/product/B00FBE197I?keywords=Ns1000%20headphone&qid=1451589484&ref_=sr_1_1&sr=8-1