The Sennheiser HD 660 S was launched as a replacement for one of the most legendary headphones in existence, the company's own HD 650. It had a pair of massive shoes to fill and managed to do just that. To my ears, the HD 660 S is a clear sonic upgrade to every possible aspect of both the HD 600 and HD 650. I wouldn't go so far to say that you should buy them if you already own and like the HD 600 or HD 650, but if you're looking for your next pair of hi-fi headphones and are deciding between all three of them, definitely go for the HD 660 S.

With a price tag of $500/€500, the HD 660 S does cost quite a lot. If you don't already own a good headphone amplifier, which you'll definitely need to use it to its fullest potential, that's going to be an additional expense. However, once you buy it all, you're done, quite possibly for good. The sound performance of the HD 660 S is certainly high enough for it to be your final endgame pair of headphones, and that's as big of a compliment as I can give it. The HD 660 S sounds musical, smooth, crystal clear, natural, open, and airy. It offers plenty of attack and snappiness in the low-end, excellent vocals, as well as an impressive amount of detail, and is also terrific in a gaming environment. Once you hear the level of accuracy the HD 660 S offers in terms of spatial positioning, you'll start regularly connecting it to your PC for your gaming sessions.

Their biggest issue—a high clamping force out-of-the-box—can be resolved manually with a bit of patience. You can't do much about the plastic construction, though, if that's something that bothers you. It's a smooth, sturdy, and creak-free variant of plastic, but it's still plastic. I for one won't judge you if you're expecting more luxurious build materials at this price point. In terms of sound quality, not much is happening in the sub-bass region of the frequency spectrum. If you're all about electronic music, namely artists who use heavily synthesized basses, you're probably better off looking at a different pair of headphones with a stronger emphasis on the lowest of lows.

For everyone else, the Sennheiser HD 660 S is a highly versatile, fantastic-sounding pair of headphones. If you have a quiet place in your home where you can sit back, relax, and enjoy the music, and $500 to spare, get it. You can thank me in the comments!