We approached Sennheiser’s top headphones, the HD 650, with high expectations, as person to person for the merchandise has been overwhelmingly positive. The headphones certainly look the part; the HD 650s’ luxurious feel, the thickly padded headband and ear cushions, and the titanium-silver finish leave no doubt–even before you hear them, you can tell these are incredibly special headphones. The HD 650s are pretty big and moderately heavy (9 ounces), but they’re extremely comfortable. We logged many, many hours of listening time and came away thoroughly impressed with their comfort. They retail for $550.

The headphones’ drivers are hand-selected to make sure precise left/right matching tolerances and show computer-optimized neodymium magnet systems to reduce distortion. Their lightweight aluminum voice coils ensure accuracy and fast transient response. The HD 650s’ 9-foot Y cable is user-replaceable, and that is a very important thing because through the years, cables inevitably break. The cable is terminated with a 1/4-inch plug, and a high-quality miniplug adapter is roofed.

The Sennheiser HD 650s are designed for home instead of lightweight listening–they’re too large and bulky for on-the-go use. The headphones are also rather power hungry, so puny iPods and MP3 players won’t supply enough juice to create much volume. Knowing that, we conducted our auditions on a home-theater system. We first popped on the Master and Commander DVD to explore the limits of the HD 650s’ home-theater prowess. The naval battles’ cannon fire exchanges never came near fazing the Sennheisers. Bass was fuller than that of any other headphone we’ve ever used, and the sound seemed to result from the other side of the area.

There’s a sweetness to the HD 650s’ open sound that flatters a variety of music. The detail is all there, however the treble frequencies are more relaxed than those of the Grado RS-2 headphones ($500). Hard-rockin’ tunes sounded just a little tame over the HD 650s, and a switchover to the RS-2s pumped up the excitement factor on Neil Young’s Ragged Glory CD–the enriched blasts of raucous energy from Young’s guitar sounded more realistic over the RS-2s. But we’d the opposite reaction whenever we played acoustic music, as the HD 650s why don’t we feel more of the weight of Cyrus Chestnut’s grand piano on his Revelation CD. The HD 650s’ superclean sound encourages listening at a higher volume, even at levels that might be painful with other headphones. The HD 650s’ bass is bigger than that of the RS-2s, however the RS-2s’ definition clarifies details lost to the HD 650s. We heard texture way down in the mix in the RS-2s; details including the bass player sliding his fingers over the strings are harder to listen to on the HD 650s.

The Grado RS-2 and the Sennheiser HD 650 are both reference-quality headphones, and we’d be thrilled to live with each one, although they sound completely different in one another. The HD 650s had somewhat more style and a boomier sound, but you will lose a small amount of sonic detail. Your purchase may finally boil right down to what you’ll be hearing.