The HD800S and HD660S2 are Sennheiser’s two top open-back headphones at the moment. The HD800S was launched in 2016 and is the revised version of the HD800, launched in 2009. The HD800 had a completely new design and drivers, created from scratch aiming to be the best dynamic headphone in the world.
The HD660S2 has a longer heritage. Starting with the HD580 in 1993, which was the first to have the oval shape and head-band that should be one of the most recognisable designs in headphone high-fi, the iconic design of the HD6** series. The HD580 was followed by the HD600, HD650, HD660S and finally HD660S2. Until the launch of the HD800 in 2009, this was the flagship series from Sennheiser. The mini-HD800, the HD700, came along in 2012. It was filling the gap between the HD600/650 and the HD800. Even though the HD700 had many good qualities, it never became a huge hit. It is nonetheless a very interesting headphone when discussing the HD660S2 because according to various non-official sources, the driver used in the HD660S is very similar to the one used in the HD700. Further, the HD660S2 driver is officially a modification of the HD660S driver. So in a way, the HD700 might live on in disguise.
As mentioned, both headphones are open-back dynamic driver headphones. The HD800S has a 56 mm ring radiator, i.e. the driver is donut-shaped and has a big hole in the middle. The HD660S2 has a more conventional 38 mm driver. Both headphones are 300 Ohms. The HD800S has a sensitivity of 102 dB SPL@1V, the HD660S2 is slightly more efficient at 104 dB. The specifications are very close with regard to what load they present to an amplifier. This might make them a compelling duo if you’re looking for complimentary headphones. Because, as we will see, they have different strengths.
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COMPARISONS
To compare these two headphones I use three amplifiers. Two solid-state amps in different price classes and one tube amplifier. I regard all three to be a good match for both headphones.
QUESTYLE CMA800R
This amplifier was built for the HD800, and is a very capable and delicious-sounding device. I find it to be a good match for both headphones. Even though it has been discontinued the technology lives on in the Questyle CMA 400i and CMA15 DAC/amps.
Cascade 1 by Thomas Agergaard
This is a tender piece with a duo playing saxophone and piano. The HD800S is very open and spacious sounding. I am really surprised by how close they actually sound. The tuning isn’t that dissimilar at all with this track. The HD800S sounds more spacious and has better detail. The HD660S2 has more presence in the mid-range, but not as much as I’d expect.
10:15 Saturday Night by The Cure
Here they are much more different. The HD800S has an immensely spacious presentation. The HD660S2 isn’t even close, it sounds inside your head and muffled in direct comparison. However, that’s not to say it’s bad or not enjoyable. The HD660S2 is punchy and with good separation and a nicely balanced tonality. However, it just cannot match the HD800S’ strong sides.
Angel by Massive Attack
The bass is very tactile and tight with the HD800S. With the HD660S2 it’s less defined and looser sounding. The vocals are much more upfront with the HD660S2, but not as warm as I’d expect from a pair of HD6** headphones. Thus, for comparison, I bring out the HD650. It sure is warmer sounding. The tonality of the HD660S2 is somewhere between the HD650 and the HD800S. It is however closer to the HD650 both in terms of soundstage, tonality and resolution. HD800S is very detailed and spacious sounding – as always.
In My Tree by Pearl Jam
When I am at it, I start out comparing the HD660S2 with the HD650. The vocals are definitely warmer sounding and more present with the older brother. I will do a thorough comparison in another article but it was interesting to check out the HD650 in this context.
Anyway, this track sounds good with the HD660S2, although I prefer the mid-range timbre of the HD650.
I love the drums on this track. They sound good with the HD800S but they have an even nicer and fuller sound to them with the HD660S2. The vocals are more distant with the HD800S. The HD660S2 again sits somewhere between the HD650 and HD800S. For some reason, this track sounds a lot better with the HD660S2 (and even more with the HD650…) than the HD800S. The HD800S gets fatiguing and distant sounding.
It Could Be Sweet by Portishead
The bass and treble are cleaner with the HD800S, and the mid-range is more present and natural sounding with the HD660S2. Beth Gibbons’ vocals sound very distant with the HD800S, while the bass is a bit bloomy with the HD660S2. Sound-stage is also a win for the HD800S.
Prokofiev – Sonata for 2 violins op. 56 by Janine Jansen
The HD800S is hard to beat here. The airy and delicate presentation is simply delicious. The HD660S2 is nice, a bit more meaty and intimate but not as refined.
Prokofiev – Violin Concerto no 2 op. 63 by Janine Jansen
It is the same thing here, the HD800S has an incredible way of presenting strings and orchestral music. The fabulous soundstage and rich detail is hard not to like.
MONOLITH THX AAA 887
This little amplifier is becoming one of my favourites in its price class and delivers a very neutral and powerful sound. It is supposedly very similar to the THX AAA 789 from Drop (which I have yet to hear).
Ragged Wood by Fleet Foxes
The HD800S is a lot cleaner sounding here, while the HD660S2 feels a bit disorganized with this busy track.
Come Away with Me by Norah Jones
I find that the vocals are better sounding on the HD660S2. However, the spaciousness and detail level of the HD800S are on another level and create a sense of delicacy and nuance not there in the little brother. Both are enjoyable, though.
In My Tree by Pearl Jam
As with the Questyle, I find the HD660S2 more enjoyable albeit lacking in resolution and soundstage. There is something off with the distant presentation the HD800S delivers. Sometimes it’s right, sometimes not.
It Could Be Sweet by Portishead
Unlike with the Questyle, I do not really prefer the mid-range of the HD660S2 that much here. I tend to find that the Questyle is a relatively better match for the HD660S2, while the HD800S does fine with either.
I keep on playing more tracks and I conclude that I find the Monolith THX AAA 887 to be really good sounding with the HD800S. The HD660S2 does better with the Questyle. Thus, on the Monolith I tend to systematically find the HD800S preferable.
WOO AUDIO WA22
The WA22 is a favourite both with the HD800/S and the HD6** series. It’s a balanced transformer coupled tube amp.
It Could Be Sweet by Portishead
As with the Questyle, the vocals of Beth Gibbons’ are more delicious with the HD660S2 and the midrange isn’t lacking in detail either. The bass and treble, however, are cleaner with the HD800S.
In My Tree by Pearl Jam
Also here, I find the HD800S’ mid-range a bit recessed compared to the HD660S2. Otherwise, it’s better.
Midnight City by M83
The HD660S2 is punchy and entertaining. The bass drum hits really hard. Again, the HD800S takes a few steps back making you more of an observer than a participator, relatively speaking.
Bored by Deftones
The HD660S2 is so much more visceral sounding. You can feel the drums and the bass and the general presentation is a lot more enjoyable with this music. The HD800S becomes quite anemic.
I continue listening to the same tracks as I used with the other amplifiers. Even though there are differences between the three amplifiers, the pattern seems to be quite consistent when it comes to comparing the two headphones.
WRAPPING IT UP
In terms of treble resolution, there is no contest; the HD800S is far ahead. However, it is also more fatiguing. With regards to midrange clarity, I find the HD660S2 just as good and it also has a better presence and more body. The lower regions are also significantly more present with the HD660S2; there is more weight and punch in the bass region. With regards to resolution in the bass, the HD800S is quite a bit better, it’s also more linear with more perceived sub-bass.
When it comes to the soundstage, the HD800S is deeper, taller and wider, with better placement of instruments and more space between them. It has got superior imaging, creating a more holographic experience. However, it does sound a bit distant, making you more of an observer than a participator.
The HD800S is clearly better with microdynamics and subtle detail. The HD660S2 is more about macro-dynamics, punch, and presence. In addition, it has a more balanced sound signature. The HD800S has a bright leaning sound signature with a somewhat recessed mid-range and polite bass. It’s a very analytical headphone. The HD660S2 is putting you more on the stage, as opposed to sitting in the 10th row in a concert hall.
CONCLUSION
The HD800S is without doubt technically superior to the HD660S2. It offers more detail and the soundhstage is extraordinary. However, the HD660S2 has something else: A more balanced, well rounded sound-signature and better visceral qualities. There’s simply put more slam and punch.
Now, die-hard fans of the HD800 and HD800S will say that if you just give them the right sort of expensive tube amplifier and a 1-inch thick ultra-pure-oxygen-free cable, everything will be fabulous. And for sure, the amp does really make or break the performance of the HD800/S. I have tried my fair share of amplifiers, and a good amplifier match will both tame the worst treble peaks as well as bring some more warmth the sound of the HD800/S. For many listeners that does the trick. The ones I have used here in this test are quite good, but there are even better options. You can check out some of my experiences here.
My personal favorite is the EAR HP4. However, that is a very expensive piece of equipment and it will make the setup ridiculously more expensive than a good HD660S2 setup. I’m not saying it ain’t worth it, but it is what it is.
The HD660S2 is almost ⅓ of the price of the HD800S. Still, regardless of price, I think many people would be more happy with the HD660S2 than with the HD800S. Why? Because it has a more easy going sound signature. It will simply be a better all-round performer for most people. It’s got more punch, is warmer sounding and less analytical. You can play louder without fatigue.
Until Sennheiser manages to make an iteration of the HD800/S with a more natural and easy-going sound signature, there is a real trade-off between the HD800S and the smaller siblings (HD600, HD650 and HD660S2). Do I enjoy the HD800S? Absolutely. Is it impressive and fascinating? Yes, indeed. Would I have it as my only headphone? Not so much. But hey, that’s just me.
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SPECIFICATIONS HD660S2
- Wired
- Circumaural / around the ear
- Open back design
- Dynamic driver
- Frequency range: 8 – 41,500 Hz
- Impedance: 300 Ohm
- Sound pressure level: 104 dB (1V)
- Driver size: 38 mm
- Distortion factor: <0.04% (1 kHz, 100 dB)
- Velour ear pads
- Two-sided cable routing
- Weight: 260 g
- Colour: Black
- Incl. 1.8 m cable (6.3 mm stereo jack), 1.8 m cable (4.4 mm balanced), 6.3 mm to 3.5 mm stereo adapter and carrying pouch
- Made in Ireland
SPECIFICATIONS HD800S
- Wired
- Circumaural/around the ear
- Open back design
- Transducer principle: dynamic, open
- 56mm Ring Radiator dynamic transducer system
- Sensitivity: 102 dB (SPL @ 1 V)
- Impedance: 300 Ω
- Frequency response: 4 Hz – 51,000 Hz
- Total harmonic distortion (THD): < 0.02 % (1 kHz 1 Vrms)
- Magnetic field: 10.5 mT
- Cable connector on headphones: Proprietary 3-pin connectors.
- Cable length 3 m x 2 cables
- Cable with 6.35 mm jack plug
- Cable with balanced 4.4 mm jack plug
- Included in the box: Headphones. 2 x 3m cables: One unbalanced 6.35 mm TRS and one balanced 4.4 Pentaconn. User manual.
- Article number (SKU): 506911
- Weight 330 g
- Made in Germany.
