I found these for a great price used and couldn't pass them up because I am going on a long flight soon. The noise canceling in these is incredible as most have said. Any sound that drones on or rumbles or is generally steady and unpleasant goes away with the flick of a switch. My first test for these was my lawnmower. They can kill the sound from it to a point where it is only a very low easy to ignore sound. Music will completely drown it out. Second test was inside a data center at work. These can almost completely kill the sound from the data center. Anyone who has been in one knows what I am talking about... Lots and lots of loud fans all going at once. Interestingly enough though you can still hear people talk with these on. They are definitely quieter but if I pause my music with them on I can still hear a co worker if they are talking directly at me. I think this is by design. They are more for canceling ongoing consistent sounds not sounds that are brief and varied.
Ok now on to the sound quality. It's passable. It's good. Its not amazing or awe inspiring but it's just fine. If you hear them you would understand.
Highs are smooth but a bit compressed and recessed. Very top end is missing.
Mids are very smooth clean and forward.
Bass is slightly muddy and a tad boomy but not overstated.
Overall I would consider this sound signature to be very relaxing and easy to listen to for hours. There is nothing to wear you out. That might be exactly what Bose was going for honestly. If you think about it for this type of headphone it makes sense. Some could consider them a bit muddy sounding due to the compressed highs and the boomy bass but I really do think they sound fine.
So in conclusion I feel like if you can pick up a pair of these for $150 or less they are worth it. I couldn't see spending any more on them. If they sounded better they would be worth the $300 price tag. Also as others have stated you have to have them turned on for them to put out any sound at all. If your batteries die you are out of luck. I also don't like the cable. It's a bit tangly and doesn't like to straighten out if you have had it rolled up for a while.
Ok now on to the sound quality. It's passable. It's good. Its not amazing or awe inspiring but it's just fine. If you hear them you would understand.
Highs are smooth but a bit compressed and recessed. Very top end is missing.
Mids are very smooth clean and forward.
Bass is slightly muddy and a tad boomy but not overstated.
Overall I would consider this sound signature to be very relaxing and easy to listen to for hours. There is nothing to wear you out. That might be exactly what Bose was going for honestly. If you think about it for this type of headphone it makes sense. Some could consider them a bit muddy sounding due to the compressed highs and the boomy bass but I really do think they sound fine.
So in conclusion I feel like if you can pick up a pair of these for $150 or less they are worth it. I couldn't see spending any more on them. If they sounded better they would be worth the $300 price tag. Also as others have stated you have to have them turned on for them to put out any sound at all. If your batteries die you are out of luck. I also don't like the cable. It's a bit tangly and doesn't like to straighten out if you have had it rolled up for a while.
I'm surprised you thought the highs were recessed. I owned a QC15 for years, and the highs were boosted and often sibilant, but less so with a proper cable.