Everyone is aiming for clarity, but just like camera manufacturers, each high-end headphone brand brings its own flavor to the experience. Fans love Sennheiser’s HD 600 series not only for its remarkable definition and dynamics, but also for the subtle way it expresses those revelations. Unlike some headphones that can sound more “clinical” or crisp and cold, there’s a smoother grain in the midrange and treble, while still allowing full distillation of all frequencies. (The declared total frequency response is 10 Hz to 41.5 kHz.)
The 660S2 builds on that sound with an added drop of amber in the sound, for an even more saturated color that’s more pronounced in the low end. Bass may be the biggest reason to consider these over more affordable models in the series. Dropping the needle on hip-hop and electronic tunes unleashes an extra surge of fundamental power, and can be a lot of fun to listen to.
The main beat on Biggie’s “Hypnotize” is a laser punch with exceptional balance. It’s a funkier sound than the boom you’ll get from cheap bass bombers, almost rewriting the overall feel with a jazzier flavor. Similarly, Too Short’s “Money in the Ghetto” has a sweet button punch on the lead kick that’s expertly articulated. Those aren’t my usual tracks for these types of headphones, but they helped set the stage and sounded great doing it.
The Chemical Brothers’ “Go” is an even more intriguing test case, again showcasing the 660S2’s bass chops and also highlighting its lightning-fast transient response. The song’s kick drum is carved with a deep echoing reverb texture that expands like a bubble in the center image. Excellent instrumental spacing lets you roam freely across the dimensional soundstage, from the synth sweeping through the stereo image before the chorus to the build-up in instrumental breakdown that feels like an impending rocket launch.
Even the hype in Maxwell’s Silver Hammer it’s got some extra flair, providing a raucier, yet refined ride than you’ll get from other models in the HD 600-series or later. I prefer the more neutral take on the 6XX for those tracks, but it didn’t hurt the experience.
Elsewhere, you get the same kind of lyrical clarity and refinement that first made me want the HD 6XX. Reverb tails echo into oblivion; piano tracks allow you to estimate both the size of the room and the placement of the microphone – the nerd in me was asking, “Was it a close-up with the lid open of a grand piano outlined with the room’s microphone? ” (I think it was). The distorted guitar in ELO is so textural and visceral that it gives me the cold, stringy crunch of biting into a popsicle.
Even podcasts have richer representation, letting you hear not just how close the microphone’s vocals are beat-for-beat, but also deeper details like whether Sean Hayes took dairy before the intelligent Jon Favreau interview (he definitely did).
It is all, in a word, glorious. But to my ears, the HD 660S2 isn’t so much an improvement over other headphones in the series as a slightly different version. Fabulous headphones all, I’m more interested in the best value. As I write this, you can get the original 660S at $320not to mention the surprisingly affordable 6XX at $219. Additionally, I found the 6XX to be the more comfortable of the two I’ve tested, which is an important consideration for long listening sessions.
If you’re excited about extra bass, richer saturation, and even tighter bending on your head, there’s an audiophile wonder in the HD 660S2. Whether it’s worth the extra coin is up to you and your wallet.