Summary: • yes, there is a slight "hiss"with noise cancelling enabled. But, I don't know of another make that doesn't do this. It's inherent to the technology that in cancelling the ambient noise, some additional "hiss" is created due to imperfect cancelling. But in a noisy environment, the hiss is much quieter than the background noise it's cancelling out.
Pros: • compact size / easy to travel with
Cons: • battery compartment a little bulky and somewhat awkwardly placed - if you don't have a button-up shirt or a shirt with pockets, it's hard to find a place to clip it. Clipped to my belt it will pull the buds out of my ears if I move in certain ways. Leaving unclipped pulls at the buds and isn't really an option. Ideally it would have 3" more wire on both sides of the battery compartment. Of course, I'm 6'4", so the length/placement may be perfectly sufficient for the...
Summary: * I barely notice a difference with the noise cancelling on/off. I get a slight noise/hum when the noise cancelling is on and the music volume goes about 10% quieter as well. You don't notice the noise/hum when listening to the music though.
Pros: * Can't argue with a half price shell shocker
Cons: * Compared to my Sennheiser CX300's which were a fraction of the price, the Pioneers didn't fit as well and I had to crank it up around 20% more for the same amount of music volume.