Sennheiser HD 660 S vs Hifiman Sundara Comparison Review

Sennheiser HD 660 S vs Hifiman Sundara Comparison Review

I’m about to compare two of the best selling headphones in the $500 price range. But these two sets of cans sound vastly different. Which better suits your taste, and which one is objectively superior in overall sound performance? Let’s find out in this Sennheiser HD 660 S vs Hifiman Sundara Comparison Review.

Sennheiser HD 660 S vs Hifiman Sundara Comparison Review

IN the BOX – Sennheiser HD 660 S vs Hifiman Sundara Comparison Review

Sennheiser HD 660 S Hifiman Sundara
Removable cable with 1/4″ (6.35mm) plug Detachable cable
Removable cable with 4.4mm balanced Pentaconn (5-pin) plug
1/8″ (3.5mm) to 1/4″ (6.35mm) adapter cable -3.5mm-6.5mm adapter


FIT and AESTHETIC DESIGN – Sennheiser HD 660 S vs Hifiman Sundara Comparison Review

The HD 660 S and Sundara are very different in physical design. Both are open-back, but the Sennheiser has oval ear cups, while the Hifiman’s are round. In terms of fit, I like the Sundara a lot more. The round shape of the Sundara fits comfortably around my ears, while the oval shape of the HD 660 S is a little too narrow.  The headband on the HD 660 S has comfy cushioning, and the earpads are made from soft material. The Sundara has a two tiered headband. A thin but wide headband floats under a metal headband. The earpads have leather on the edges, while the interior is made from soft material. The Sennheiser is a lighter and much simpler headphone than the Hifiman. But the Sundara looks a lot cooler.  The difference in weight doesn’t bother me because both headphones feel pretty light.

TECHNOLOGICAL DESIGN – Sennheiser HD 660 S vs Hifiman Sundara Comparison Review

One of the reasons that these two headphones sound so different is that the HD 660 S has dynamic drivers, while the Sundara is planar magnetic. I don’t think that either technology is superior, but they do create completely different sound profiles.

Sennheiser HD 660 S vs Hifiman Sundara Comparison Review

Comparitively speaking, The HD 660 S has a deep and full character, with airy highs, while the Sundara is defined by its clarity, separation and beautiful imaging. Let’s see the breakdown.


The lows on the HD 660 S are a little thicker and deeper than the lows on the Sundara. The HD 660 S convey a little more texture in the bass. The Sundara has a clearer, more refined sound with greater separation. Both are fun to listen to in the pop, hip-hop and EDM genres. But the lows are a bit more enjoyable on the HD 660 S when listening to fuller mixes, like rock, simply because the bass is more present.


Boy, do I love mids. Usually I’m a sucker for the warmer, richer sound in this range. So, I assumed that I would prefer the HD 660 S. But the gorgeous separation conveyed by the Sundara is so superior, that I’m willing to compromise fullness for detail. Rock lends itself a little better to the HD 660 S, but every other genre sounds a lot better on the Sundara. The clarity and presence of the vocals on the Sundara, for example, make it a more satisfying listening experience. In comparison to the Sundara, the HD 660 S almost sounds congested and muddy. And I would never usually describe any Sennheiser headphone in these terms! But when listening to practically every instrument, from percussion to acoustic guitars, the detail and crispness on the Sundara wins every time.


Listening to high strings and choirs, I felt like the HD 660 S did a better job of conveying texture and airiness, while the Sundara was again more refined and clean. I enjoyed the softness and slight roundness of the HD 660 S when listening to classical. I would have to say that the classical genre in this range sounds more moving on the HD 660 S. But with other genres, namely, folk, pop, and EDM, the crisp transparency of the Sundara takes the cake.


Both headphones have a nice, wide soundstage. But the Sundara seems a bit more spacious, and the imaging feels a lot more accurate. The Sundara also has more depth and height.

SUMMARY – Sennheiser HD 660 S vs Hifiman Sundara Comparison Review

While both headphones are excellent in quality for the price, the Sundara is much more elegant in its presentation. If you enjoy a very full and deep mid range, you may prefer the HD 660 S. But if you value clarity, speed, separation, and super accurate imaging, then the Hifiman Sundara might be the one.

You can find these headphones for the best price at:

Audio 46: Hifiman Sundara Open-Back Planar Magnetic Headphones

Audio 46: Sennheiser HD 660 S Open-Back Headphones

Amazon: HIFIMAN SUNDARA Over-ear Full-size Planar Magnetic Headphones (Black)
Amazon: Sennheiser HD 660 S – HiRes Audiophile Open Back Headphone

SPECIFICATIONS – Sennheiser HD 660 S vs Hifiman Sundara Comparison Review

Hifiman Sundara

Sennheiser HD 660 S

Frequency Response 6Hz – 75kHz 10 – 41 kHz
Impedance 37 ohms 150 ohms
Sensitivity 94dB 104dB
Weight 372g 260g
Type Planar Magnetic Open Dynamic Open