Summary: I also have a pair of Sennheiser 419, the soul's blow them away in sound quality.
Pros: One of the best sounding headphones that I've heard. Excellent sound isolation as well as limiting external noise. The sound canceling works well. Isolates most outside noises immediately (except for close loud conversation, but dampens it significantly).
Summary: I can't believe the level of quality and the popularity that headphones have experienced in the last few years. I built my first amp from a kit when I was 12 and still love audio. For all you old farts out there, don't overlook these because they are named after a Hi Hop artist. This is one of the best pair of cans I have ever owned.
Pros: Extremely efficient (easiest to drive of 15 pairs of cans I own!) Light weight, ear pads claim "memory foam" but no matter what it's made of, they feel great. Fantastic isolation from exterior noise even when noise cancelling off. Solid low end without being boomy. Highs shimmer (like a cymbal is suppost to) not scratchy like sand paper. One of the few cans I own (Sennheiser, AKG, Klipsch,Audio Technica, Able Planet, Koss )that creat an actual sound stage.
Cons: Gold/b lack color (I'm 59, but how do you pass up $89 for these). Allot of plastic (they fell somewhat cheaply made). Narrow 3.5mm jack that will probably only accept the 2 cords that come with it. A zippered hard shell case that is cheaper than my Klipsch or Able Planet. Large size (these are full size phones and will put some people off who want to use noise cancelling phones only for travel).
Summary: These headphones are definitely meant to be listened to on the high noise cancellation setting with the volume turned up. (higher volumes is where this product shines). That doesn't mean blowing ear-drums loud, but if you typically have the volume on a lower settings I'd suggest saving some money and getting cheaper set.