But audiophile headphones like the Sennheiser HD 6XX go another route ... Of the ones not already mentioned above, the HD 560S ($230) and HD 660 S2 ($600) are the most compelling.

and the HD 505 sits just beneath the Sennheiser HD 600 in the line-up. Sennheiser says that the new headphones have an adapted transducer that was designed to give better bass and treble extension ...

The Sennheiser Accentum Special Edition (SE) headphones are down to under $150 and include the Sennheiser BTD 600 Bluetooth ...

However, as I mentioned further up, you can get the Sennheiser HD 600, which are the 'step-up' versions of these headphones, for very close to the same price as these in the real world.

Generally speaking, 500-series headphones have enjoyed wide frequency ... Perhaps the most compelling alternative, though, is Sennheiser’s own HD 600 – they’re a step up in performance ...