Sennheiser has just released an improved and retuned version of the HD 660S, the HD 660S2. Although, these two models may not prove vastly different, the HD 660S2 does take on some more charismatic qualities than its predecessor. What can you expect in terms of sound and design from this latest version? And is it worth the upgrade?

What is Included with the HD 660S2

• HD 660S2 Open-Back Headphones
• 1.8m Headphone Cable – 4.4mm Balanced
• 1.8m Headphone Cable – 6.35mm Unbalanced
• 6.35mm to 3.5mm Adapter
• Soft Carrying Case

Look and Ergonomics

I always appreciate Sennheiser’s no nonsense approach to design. Though not particularly flashy, HG 660 S2 sports an entirely solid build, from the sturdy grill on the ear cups to the strong feel of the headband. In short, these cans should be able to take the beating of daily use. Although the clamping force is quite firm, the the velour ear pads keep the ears comfortable and cool even throughout long listening sessions. No complaints here.

Design and Changes from the HD 660

In this latest iteration of the HD 660, a few major changes have been implemented. First, Sennheiser has improved its transducer, which in theory should increase sensitivity throughout the frequency spectrum. The weight of the voice coil has also been reduced, improving the transducer airflow and minimizing resonance. And in general, the enhancements on the HD 660 S2 lend a warmer and more fluid feel to the overall sound signature, compared to the original HD 660. Lastly, impedance has been raised from 150 Ohms to 300 Ohms. Some listeners may opt to use a small desktop amp. But personally, I found that my little Dragonfly Cobalt gave me sufficient power. So, even a small, portable DAC/Amp should do the trick.

Like the HD 660S, the HD 660S2 comes with both, an unbalanced 1.8 meter cable with a 6.35mm connector and a 1.8 meter balanced cable with a 4.4mm connector. In addition, you’ll find a 6.35mm to 3.5mm adapter in the box.

Sound Impressions

Soundstage

Expect a thoroughly engaging and generously spaced-out soundscape. In addition to the wide stereo field, there’s a real sense of depth here. Instruments can really sit behind the head on these cans, whereas on so many dynamic headphones, rear placed instruments seem to be contained to the stereo boundaries.

But here, you’ve got a truly multidimensional feel. Although you won’t hear soaring heights in instrument placement, the HD 660S2 does seem to elevate instruments, especially in the upper-mids, adding to the levitational quality of the sound signature overall. And I would say, as far as reference headphones go, this is one of the most enjoyable soundstages I’ve experienced. I would even venture to say that the soundstage beats some of the higher priced planar magnetic models on the market.

Low-End

Though you’ll hear a thick and substantial bass, it remains disciplined enough to stay in its lane for the most part. So, listening to pop, I got the punch and depth I was looking for. And hip-hop tracks revealed some rumble. But as I moved to acoustic genres the bass stopped short of taking center stage. Still, because of generous lows, instruments such a cellos and double basses have meaty and majestic quality. Transparency may not reach the level of some similarly priced reference headphones, (such as the Beyerdynamic DT 1990), and some of the more nuanced textures of acoustic instruments seem to be slightly smoothed over. But on the flip side, this profile brings a pleasing fluidity to the sound.

Mids

Although you’ll hear a relatively even balance in this range, the low mids seem to come out in full force, borrowing some of their power from the warm low-end. At the same time, the upper mids never sit too prominently, so you won’t hear any harshness or unnaturally forward vocals.

And the most enjoyable aspect of this range lies in the fact that instruments in the high mids seem to float through the mix like a cool breeze. Vocals are super airy, and guitars feel effortless. It’s a super chill sound that handles instruments with a degree of softness that you won’t find in other reference style headphones. So, the HD 660S2 is a refreshing contrast to analytical cans that often feel unemotional because of their strict focus on precision.

High-End Response

Like the upper-mids, the highs seem to defy aural gravity, making female vocals and pianos glide gracefully through the space. Never heavy handed or sterile, there’s a smoothness here that makes these so-called reference cans an exceptionally enjoyable listen. At the same time, you certainly won’t miss out on the highest treble frequencies, and there’s enough extension here to accurately reveal the peak treble notes of instruments like violins and trumpets. In fact, at rare moments, the highest frequencies can almost cause a bit of discomfort at louder volumes.

Specifications

Summary

It’s clear that Sennheiser not only had sound professionals in mind when creating the HD 660S2; this headphone is meant to be enjoyed and appreciated for its tender handling of instruments as well as its fantastically buoyant character. And although the HD 660S2 might not reveal as much detail as some popular analytical headphones at this price point, it would still be my personal choice for the studio as well. Because at the end of the day, music needs to sound musical. And the HD 660S2 certainly achieves that quality.

Finally, for those who own the HD 660S, and are looking for a deeper bass with more extended highs, the HD 660S2 should deliver these improvements. Is the HD 660S2 worth buying if you already own and are happy with the first model? Sure, but opting for a different brand with a completely different sound signature might be a more interesting addition to your arsenal. 

You can buy the Sennheiser HD 660S2 at Audio 46 using the button below: