Sennheiser HD660S Review

Sennheiser HD660S on Amazon

General information

  • These cost is $500
  • Use Dynamic drivers (drivers are supposed to be better than those on the HD650, possibly from the HD700)
  • Almost identical physical design to the Sennheiser HD650
  • Comes with a 1/4″ cable, 1/4″ to 3.5mm adapter, and they do include a balanced cable
  • They have a lower impedance than the HD650, the impedance on the HD660S is 150 ohms compared to 300 ohms on the HD650 which will make these easier to drive


If you’ve seen or own the Sennheiser HD650, then you won’t see many surprises here. This is pretty much the same as the HD650. The gray color HD650 with the clearcoat is traded in for the traditional matte black plastic finish. Some say that it makes the heapdhones look cheap, but I don’t think so. The headphones are primarily made of plastic except for the side grilles and the metal for adjusting the headband. The headband cushion on top works great, and the velour earpads are very comfortable and seem just a little deeper than the HD650. The HD660S headphones actually feel just a bit lighter than the HD650. Even though these are primarily made of plastic, they look very well made and look like they will last for a long time, I did not find any build quality issues like I did with the HifiMAN Sundara.


  • I prefer this simple matte black color over the bolder color of the HD600 or HD650
  • The velour earpads are very comfortable and I can wear these headphones for a long time
  • The ear pads are also deep enough where my ear is not touching the driver
  • They have just the right adjusments to make them fit well on my head
  • I like having a super long cable (although it can get in the way sometimes)
  • I like the simplistic logo on top of the headband as well as the updates grilles with the small sennheiser logo


  • As another reviewer mentioned there are no markings on the headband to tell you at what height setting you have adjusted the headband to for each side…so its a guessing game sometimes as to what height it as set at, and sometimes it skips a few notches when you are trying to set it…you either have to take your time doing it or visually compare.
  • These headphones come with quite a bit of clamping force out of the box that it can get unconfortable at times, however you can probably remedy that by stretching out the headband either manually or by leaving them on a block or something like that
  • Other than that…there is not much that I don’t like about these headphones….these headphones are actually pretty darn good



I’ll start off by saying that these are a great sounding set of headphones. Let’s start with the obvious comparison….do they sound better in my opinion than the HD650’s? I say YES! Now, should you go and sell your HD650’s and buy these…probably not, but if you are shopping for new headphones you’re probably better off saving an extra $130 and getting the HD660S instead of the HD650 given that the HD650 are currently selling for $370 on Amazon as of the making of this video.

Now let’s get into more detail about the sound.
These have a good reference level sound with a bump in the bass. I would say that they have more bass than the HD650.
I would say these headphones are on the warm side
These headphones have good treble
Great controlled clean bass
They have a mid level soundstage, definitely smaller soundstage than something like the M1060’s. Instruments definitely sound closer to you than when listening on the M1060s.
Imaging is excellent on these you can clearly determine where all the sounds are coming from.
String instruments sound great
The headphones do sound slightly veiled, but this also makes these less fatiguing and therefore was able to listen to them for longer when compared to other headphones
Vocals are easy to listen to, but again slightly veiled
Overall a less in your face sound and more analytical


They work really well for gaming, they are very clear. Able to tell where footsteps are coming from, even where they are above you.
Except for the clamping force, they were very comfortable to wear so gaming for a a few hours with these was no problem.
Your ears are not going to sweat since these have the velour earpads.
Overall I do recommend them for gaming and you can easily add a modmic5 to these to make them into a headset.


These are my favorite set of Sennheiser headphones and you are probably better off with these over the HD600 or HD650. You definitely can’t go wrong these, they just produce some great clean reference sound with a bump in the bass. If you are looking for dynamic open back headphones, these are the ones to get.

If you like the sound of open back Planar Magnetic headphones you might want to look into the new Hifiman Sundara if you can find a set that does not have the build quality issues I experienced and you prefer brighter sounding headphones. The Hifiman Sundara cost the same as the HD660S at $500 and are a very light set of planar magnetic headphones. If you don’t mind your headphones being a bit on the heavier side then you can get the Monolith M1060 planar magnetic headphones at the cheaper price of $300.

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