What's the best way to arrest rapidly moving showgoers and convince them that your noise-cancelling headphone technology is the best? Sennheiser plopped a couple of plane seats (first class, of course) on the show floor with a speaker between them spewing recorded jet turbine noise. I then sat down next to the speaker, put on the cans, and got the point. The PXC 450 is comfortable, despite its ear-enveloping size, and sounds full, rich, and spacious, with profound bass.