Sennheiser HD660s Reviews

HD 660 S has a full-size open-back design and is inherited, developed based on HD 650 / HD 600. Their shape is quite similar, but the sound quality is quite different (it’s actually HD 650, depending on the production year, they are different in sound quality. The components inside the HD660S, according to the introduction of Sennheiser, are carefully selected and fully handcrafted in Ireland, according to the company representative, because it has a sufficiently pure water source to make diaphrams (loudspeaker). .

The impedance of only 150 Ω, HD660S will be very flexible when combining with many different system settings but I still encourage you to listen, use at least one portable amplifier, for example Fiio Q1 MK2 and above If possible, use headphone amplifiers with high power, so as possible.

Open the box

HD660S is shipped in foam lined containers according to Sennheiser product standards. The box size is quite large to minimize the impact of impact if any during transport. The accessory included with the headset is a 1/4-inch (6.35mm) jack disassembled cable and an additional detachable cable with a 5-pin 4.4mm balanced jack, plus a 1/8-inch-to-1 adapter. / 4-inch (3.5mm-to-6.35mm).

Main design

HD660S has a simple, practical design. At first glance, it is quite similar to the HD600 / 650 series but there are still minor differences to distinguish from the products of their seniors. The most obvious is the mesh on the back, paint and driver structure. Sennheiser also has a better coating on the headband to resist peeling after a good time with a lot of sweat, solving the annoying problem of the form that has been on HD600 / 650.

Feeling of light wearing, accompanied by an elliptical earcup design hugging the ear ring with sufficient pressure. The earpad of the headset is quite thick, with a tightening of the tightness, wearing an air-conditioned room is not uncomfortable, hot or mysterious. HD660S has a volume of only 290g, calculated to be light. One point to note is that if he has a slightly larger head size, the HD660S will have a slight squeezing force on both sides. This can be solved by attaching a headset to a few books or a paper box so that it expands slowly.

Sound quality

Let us mention the HD600 and HD650 before discussing the main character in the article. The HD600 has a high-tempo and high-fidelity sound that pleases most rock fans, while the HD 650 chooses a slower and more warm approach, as well as a smooth, hard-to-find approach. see at any headset. Many people comment that the sound quality of HD 650 sounds a bit dark and this may be true in some cases, because the quality of your music also affects the sound quality of the headphones.

The HD 660 S has more crisp bass, taut and more speed, the center is still sweet, soft, but pure and delicate, accompanied by treble if compared to the previous two seniors, there is more energy, High fidelity, wide sound field, comfortable. There are many depths, but the width, spread is still a bit narrow, maybe it is new, used only 2 weeks

Bass, Mid and Treble

The bass of HD 660 S is absolutely dependent on mapping. Bass of HD660 S can switch from fast and neutral to fullness depending on the setting you are using. I listened to No New Friend or Thundercloud in Sia’s LSD album through multiple compositions, seeing the tension of the mid bass, the low-bass shape, it is directly proportional to the power of the paired amplifier

Mid of HD660S is better than bass, quite stable, the tonality is generally guaranteed and highly detailed, and if you want it to be sweeter, you have to depend on the map, dac or amplifier.

The Treble of the HD 660 S is energetic, fast, compact and unrestricted when it comes to chattering recordings of ECM Records. Anyone who is familiar with HD650 and then through HD660 S will feel full of new, treble decay too fast but not slow like HD650 anymore.

Test settings

The strongest point of HD660S is its flexibility thanks to the 150 Ω impedance. You will immediately realize that there is no need to open the volume level too high so that HD660 S can be loud enough for listening. Of course, the better the system setup, the better the performance of the HD660S will be, and a pocket HiRes player will be enough for you in most cases. HD660S however will not be able to “upscale” too much, so you should not be subjective to using it with a smartphone or mid-range player or less, then the performance of the headset will be affected.

Schiit Yggdrasil + Ragnarok

Coordinating HD660S with this Schiit combo gives fast and healthy bass, high speed, low hatch of bass, not much noise, no drag on plastic. Midrange is a bit dry, listening to Eric Alexander’s string or trumpets blowing on some of Gentle Ballads albums (one is here) with characteristic prickly, well-formed and treble bands of flying and flying and melt faster, brittle. However, according to me, this is not a match for brothers who like to listen to their love. But if I listen to this kind of thing, I will see it more properly.

Chord Electronics Mojo

Collaborating with Chord Electronics Mojo gives HD660 S a very good level of detail and spread. He is about the silky and charming team, this is the solution. More bass, whirling, slightly strong in upper bass like it increases the roundness and “edge” of bass, vibrato, softness, lightness, mid-range passion, a bit warmer in low-mid, this is why I think this composer is great for those who love music to relax, listening to genres that need a nice and smooth style. The Moble’s Treble hitting the HD 660 S is quite smooth, pleasant, not dark, it is just soft and becomes more flexible so you can rest assured.


HD660 S has quite good overall sound quality and at the reference level for headphones range from $1000 to back, the overall sound is quite flexible and flexible, making it become popular with audiophile people with long listening experience. , listen a lot. Fans who currently have HD650 or HD600 will probably skip the HD 660 S, but for beginners to jump into the world of high-end headphones, the HD 660 S is an option that is hard to ignore.

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