Sennheiser HD 660 S vs Sennheiser HD 6XX

The Sennheiser HD 6XX and the Sennheiser HD 660 S are similar over-ear headphones, but the HD 6XX are better if you're looking for a neutral sound. Both cans perform superbly in the mid-range, but the HD 6XX have a little more bass, giving kick drums and basslines more thump and rumble. Although they both have open-back designs, the HD 6XX have a much more open passive soundstage. On the other hand, the HD 660 S have a more stable fit and come with a longer audio cable.