Sennheiser HD 660s Headphone Review

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Sennheiser HD 660s Headphone Review

The new Sennheiser HD 660s is sure to be the topic of discussion for many audiophiles out there. At just $499.95, does it stand up to the rest of the Sennheiser HD 600 series headphones? And how does it set itself apart? Today, we’ll find out with this full Sennheiser HD 660s review.


Frequency Response: 10 Hz-41 kHz

Impedence: 150 ohms

Sensitivity: 104 dBSPL/mW

Type: over-ear

Drivers: dynamic

THD: .04%

Price: $499.95

In the Box

-HD 660s

-removable cable with 1/4” connector

-removable cable with Pentaconn (5-pin) connectore

-1/4” to 1/8” adapter




The Sennheiser HD 660s’s headband is made of plastic and has metal extenders. For this reason, it feels durable, but needs to be handled with respect to preserve the plastic. It has a nice, thick cushion for the head and while it is not very flexible, it is quite wide and around.


The earcups are oval-shaped, keeping in line with the HD 650. Their open back is covered with metal mesh, providing a look in at the internal workings of the headphones. Overall, the cups are large. As a result, it seems like they would fit well on many different sized and shaped ears.

My ears are tiny, and as I place the headphones on my head I notice right away how tightly the earcups squeeze the head. Perhaps this is a function of the headband shape, but regardless, it is worth noting if you have a larger head.


Like the earcups, the Sennheiser HD 660s has symmetrical and oval-shaped earpads. They have a thick, soft cushion coated with a velvet cloth material.



The high frequencies of the Sennheiser HD 660s are a bit crowded right around 12kHz. This boost forces an uneven response in the high end, but maintains a modern sound. To relieve some of the crowding, there is a cut at 6kHz.


A boost around 3.5kHz gives energy and presence to vocals, strings, and guitars. The high-mids feel particularly thick, especially when compared to the low-mids which feel too polite. Listening for too long or listening at louder volume levels results in an unpleasant mid-range aggression.


The lows in particular, in addition to the rest of the frequency spectrum, are dynamic and fast reacting. A broad boost around 150Hz gives extra punch to kick drums and other low-frequency information but in general, I wish there was more low end.


The Sennheiser HD 660 has a wonderful soundstage! Left-to-right imaging is wide and expansive. Likewise, front-to-back imaging is deep and detailed. Top-to-bottom imaging is less accurate because of the crowding around 12kHz. There isn’t enough air to give a truly tall height.


The Sennheiser HD 660s emphasize the high-mids, and as a result, sometimes feel harsh depending on how loudly you’re listening or how bright the recording is. Despite this favoritism of the mid-range, the headphones have a wonderful soundstage which makes the $499.95 price acceptable.

The Sennheiser HD 660s is available right here at Audio 46.


Sennheiser HD 660s audiophile headphones


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