Sennheiser HD 660S2 Review

Sennheiser HD 660S2

In this article we review the Sennheiser HD 660S2 headphone. It is selling for $599,95 USD.


Disclaimer: The Sennheiser HD 660S2 was sent to us by the local Sennheiser press agency in exchange for this review. Sennheiser is not related to Headfonia in any way.


Sennheiser has been around since like forever and they’re one of the most respected companies in audio. In the past, Sennheiser has impressed us with a lot of top-quality products like the HD800, the HD 800S and many 5XX and 6xx series headphones. Sennheiser has also upped their IEM game and they have successfully launched the IE 200, IE 300, IE 600 and IE 900 inear monitors.

We’ve of course featured and reviewed Sennheiser products on multiple occasions and you can find all of our Sennheiser reviews here.

In today’s review we’ll be taking a closer look at the HD660 S2, their new full sized, open headphone. The HD 660S2 is the successor of the HD 660S that was launched back in 2018 already, and it’s a direct competitor to the iconic HD 600 and HD 650 as well. Before continuing with the HD 660S2 review, I suggest reading up on the original HD 660S first. You can find that review here:

I’m also glad to see that Sennheiser after a few years will finally be present again at the High-End Munich show. The Sonova takeover surely has something to do with that. I for one look forward to visiting the new Sennheiser booth in Munich next week.

HD 660S2

The HD 660S2’s dedicated webpage can be found here. The press release is over here. It can also be directly bought from Sennheiser there. You can check out the HD 660S2 video here.

The new Sennheiser HD 660S2 features a 38mm transducer and it has ultra-light aluminum voice coil with 300Ohm impedance for excellent impulse response (150Ohm before). Of course, the HD 660S2 still is an open back design headphone and it features Sennheiser’s uniquely powerful vented magnet system for minimized distortion.

“Dive deeper into legendary sound”

For the HD660 S2, Sennheiser revised the coil of the S2, and it now matches the 300-ohm impedance of the legendary HD 600 & HD 650. This new coil also provides higher magnetic force and electrical dampening for cleaner impulse response. The surround – according to Sennheiser – is now more compliant too, dropping the resonant frequency to 70 Hz. Considerable effort also went into optimizing the airflow around the transducer. There’s more sensitivity over the entire frequency spectrum because the magnet´s air gap works more efficiently now. Taken together, these measures result in even greater precision, speed, and resolution — with double the sound pressure at the lowest frequencies.

Sennheiser HD 660S2

The biggest impact of all this is on the lower frequencies, and the HD 660S2 now shows more extended sub bass. Sennheiser states that this extension on the low-end changes everything: “by creating more space for the sound, against a deeper backdrop, the highs feel more brilliant, the soundstage deeper, and the emotions stronger”.


Transducer principle: dynamic, open

Transducer size: 38 mm

Frequency response: 8 – 41,500 Hz

Impedance: 300 Ω

Sound pressure level (SPL): 104 dB (1 kHz, 1 Vrms)

Total harmonic distortion (THD): <0.04% (1 kHz, 100 dB)

Ear coupling: Over-Ear

Weight: 260g

Adapter: 6.3 mm (1⁄4 inch) to 3.5 mm

Connector: 6.3 mm (1⁄4 inch) jack plug, 4.4 mm balanced plug

Cable length: 1.8m

Country of origin: Ireland

Magnetic field: 4.5mT

Sennheiser HD 660S2

The Box, Accessories & Price

The HD 660 S2 is officially selling for $600 USD, but it can be found online for $500 USD. The price of the original HD 660S has now dropped to just over $300 USD. The box the HD 660S2 comes in is very basic, especially for the price it is selling for. In fact, it’s very much like the HD 560S box. Is it important? No, as it’s just a box. Yes, at the whole package needs to be good.

On the inside of the box, we have multiple things:

  • The HD 660 S2 headphone
  • A 3.5 mm adapter
  • A soft carry pouch
  • One 6.3 mm cable (1.8 m – much shorter than with the HD 660S)
  • One 4.4 mm cable (1.8 m – much shorter than with the HD 660S)
  • One 6.3mm to 3.5mm adapter
  • Quality certificate
  • Quick guide

All-in-all the package is very complete, especially with the double cable option and the 3.5m adapter. With such a complete set of accessories ze immediately forget about the less impressive box. A lot of amplifiers only feature an XLR balanced connection, so you might need to get an adapter for that. I am using the adapters from Venture Electronics.

The article continues on the second page. Click here or use the jump system below.

Page 1: Sennheiser, HD 660 S2, Specifications, Box & Accessories

Page 2: Design, Build Quality, Comfort, Sound pt. 1

Page 3: Sound pt. 2, Comparisons

Page 4: Synergy, Conclusion

4.3/5 - (214 votes)

Lieven is living in Europe and he's the leader of the gang. He's running Headfonia as a side project next to his full time day job in Digital Marketing & Consultancy. He's a big fan of tube amps and custom inear monitors and has published hundreds of product reviews over the years.


  • Reply May 11, 2023


    “I do find the HD 650 to have better layering, a more natural vocal presentation, and more impressive sub rumble than the HD 660S2 […]”
    Do we need to say more? I don’t think.
    I must admit I was curious to listen to this new implementation of the classical oval-shape driver by Sennheiser, but it was a real disappointment. Too much expensive but, overall, terrible sound performances if compared to the old (but gold) HD 650. The latter has one of the best presentations ever created: there’s much better in definition, much better in soundstage, much better in dynamic, but there’s nothing better in timber than HD 650. That’s why everybody buy it (again), once realizing this.

  • Reply May 12, 2023


    what is the value of this Sennheiser HD 660 S2 compared to the Sennheiser HD 700?



    • Reply May 12, 2023


      It’s been a very long time since i heard the HD700. I’m not comfortable comparing it to the HD 660S2 from memory, sorry.

  • Reply July 22, 2023

    Steven Sylvester

    Very Good review.How do you think the HD 660 S2 would be with the

    thanking you in advance

    • Reply July 22, 2023


      Personally I would recommend an otl tube amp or a warmer/fuller solid state amp

  • Reply July 22, 2023

    Steven Sylvester

    I was taken by your super review of the FIIO Q7,so had decided to go for that Dac amp,Possibly I need to look at other partnering Headphones?I was not going to go down the tube amp route but if you could possibly give me a couple of alternatives would be very much obliged

    • Reply July 23, 2023


      It depends on your budget. You already have a dac?

  • Reply July 23, 2023

    Steven Sylvester

    I do not have anything as yet,I play my HD music files through my laptop.I only need desktop mode,not budget is approximately $1500

    I really do thank you,for the help and advice
    Regards Steve

  • Reply July 24, 2023

    Steven Sylvester

    Many thanks for the help,suggestions and advice.all very much appreciated.I will have no option but to buy via Mail-Order,as there are no good shops or wide ranging choice’s in Norway.

    May have to go for the Fiio as I can buy Fiio here in Norway,plenty to think about? once again many thanks for your time
    all the best Steve

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