Welcome to my review of the new flagship headphone from Sennheiser. The £429 Sennheiser HD 660s replaces the legendary HD 650 which was first sold over 10 years ago. So can the new HD 660s take the crown. Short answer is yes. But here’s why?

Design

From a design point of view the HD 660s look nearly identical to the outgoing 650’s. In fact, all the spare parts from the 650 will fit the new 660s. From a longevity point of view you are buying an investment and should you need to change pads, cable, in fact anything, you can just order the piece you need. The 660s take on a black paint job, with the Sennheiser logo on the grills and instead of the name Sennheiser spaced out across the top of the headband, it’s just placed on the left side. See video for visuals.

Comfort

The headphones are massive. Large ear pads comfortable fit over any ear. However, the clamping force is reasonable and due to the larger size might cause some people a little discomfort. With care it is possible to gently stretch the headband. I can wear these for hours and hours. However, I do find the cheaper HD 598s lighter and more comfortable.

Sound and Specs

The outgoing HD 600 and HD 650s were 300 ohms and therefore required some decent amplification to extract the most out of them. The 660s are now an easier to drive 150 ohms with a sensitivity of 104db. The frequency response is 10 – 41,000 Hz. Sennheiser designed these to work from some of the newer portable music devices like the LG V30 or Fiio Personal music players. However, these really need beefy amplification with decent voltage outputs to fully obtain music nirvana.

Before I tested these headphones, I gave them a 200 hour burn in. However, as you do, I had a quick listen straight out of the box and was instantly impressed. Now after 200 hours this is my verdict. The 660s are extremely detailed. Huge soundstage which has great positioning too. Speed and attack are present as well. With some of my favourite jazz, I had the hairs on my arm raise. There are very few headphones that can recreate that level of atmosphere and musicality. Bass is precise and not overdone. Being open back, you can hear everything around you and likewise anyone in the same room will hear what you are listening too. The open back design is what helps provides such a huge soundstage.

Video Review