Conclusion: The AKG K391 NC is a powerful pair of noise canceling in-canal earphones with enough upsides to compensate for its merely average noise cancellation.
Pros: Powerful bass response and distortion-free, crisp sound signature. Outputs audio in both passive and powered modes. Charges via USB rather than inconvenient disposable batteries. Inline remote control and microphone for mobile devices.
Cons: Noise cancellation isn't class-leading. The inline compartment will be an annoyance for some. Bass-boosted sound signature not for purists.
Excerpt: Up until this point, noise-canceling headphones were all a bunch of poorly designed pieces of cheap plastics costing a lot more that you've bargained for. Recent outings namely from Harman Kardon, changed all that with an attentive touch for good design.
Excerpt: The term “noise canceling headphones” almost always summons images of big puffy over-the-ear numbers. As wonderful as those can be, they’re bulky to pack if you’re traveling light, and during workouts, they suck — providing a feeling akin to sweating with scones strapped to your head.