Sennheiser HD660S2 Open Back Headphones.
RRP 949.95
Specifications
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
Rtings… does anyone who has spent much time exploring audio really use that site as authoritative?
This Hifiman vs Sennheiser is like comparing motorcycles to utes. They both have wheels and engines, and that's about it.
On the one hand you've got a famously unreliable brand that constantly updates models and obsoletes previous ones that does planars, on the other is a dynamic headphone from a company famous for being crazy reliable and supplying enough replacement parts to totally rebuild the headphones from nothing.
I have boutique planars and Sennheisers (owned the 59X, 6XX, 800S + various non-audiophile models). Both brands sound fantastic (the planars do great bass and the Senns do more 'detail') but the Senns are definitely my bash-around but great sounding headphones. They're rugged enough I've outfitted my kids with Sennheisers.
I wouldn't touch Hifiman with a barge pole- I don't like supporting companies where the owner is a POS who displays nothing but contempt for his customers. And I don't like owning products where I'd expect them to fail any time then be told tough cookies by the manufacturer.
You lost me after the first paragraph… planars will have more driver matching issues, that's just how that works.
No one is doing more for advancing the tech than HIFIMAN, not even Audeze.
While RTings are a terrible resource for headphone reviews and comparisons, I'd largely agree with that statement based on the better reviews so far.
The 660 has never really been popular, and while the S2 improves on it, it's arguably another botched chance to try and take the HD 700 driver tech and make it interesting for consumers.
Compared to the 600 and 650/6XX, you're gaining detail, imaging and separation at the expense of tonal balance (though it moves smoother through its frequency response) and less favorable timbre at times (in part due to slight wonkiness in tuning from the mid-bass through to the start of the upper mids).
If you're a fan of the older 600 series headphones, this is more of an expensive side grade, but it's a straight upgrade on the original 660. In terms of value for money, I'm more inclined to look at HIFIMAN gear as suggested above.
I've not tried the 660, not been interested because I've just heard non-flattering things about it.
But comparing these to Hifiman is just totally random and not helpful. Hifiman is a 'pays your money, takes your chances, don't cry if it backfires' kind of decision. Totally different tech, so a fairly different kind of sound, but also… just such a crapshoot.
It's really not, though I'd like to read about your first hand experience.
That reminds me, it the original 660 that had Tyll Herstens basically crying has his review, shortly before he retired.
I have the Sennheiser 6XX and Hifiman Sundara and I would recommend the Sundara over the Sennheiser. The 6XX is a bit underwhelming for everything except acoustics, vocal and classical music. Even large orchestras sound better on the Sundara. Soundstage and imaging is pretty much absent on the Sennheiser and there is a large emphasis on mid range. The planar Hifiman has better bass and treble and the soundstage, imaging is great. The details you get from planars are pretty amazing. Sennheiser plastic build quality is fantastic. I don't know what the quality issues are with Hifiman, since my Sundaras seem to have great build quality (except for the pleather ear pads that are starting to fall apart).
If I had a pick between Sennheiser 660 S2 and Hifiman Edition XS I would go with the Hifiman.
I've owned both, I now own the Edition XS and the 6XX. I'll be selling the Edition XS before the 6XX. The imaging on the Sundara falls away when you really need it in busy passages, which is true of every cheap HIFIMAN planar. Once you get up to the HE-6/Ananda/XS level in the current line-up and enclosure shapes, it gets better.
How are you driving your 6XX? Reads like you've not got enough power to control the mid-bass and push the treble extension (impedance spikes).
@jasswolf: I have a Schiit stack consisting of an Asgaard and a Modius, so I should have plenty of power for the dynamic drivers in the 6XX. I do find that I have to turn up the listening volume quite a bit in the 6XX to enjoy them. Because they are so mid-focused (and lower treble), it is not painful listening at higher volume. At a lower (or normal) listening volume they are bland.
@trippy: Ah ok, so possibly a pad/coupling issue, but I understand that it can be fairly neutral and without much sub-bass. I have them off an Asgard 3 with probably a slightly brighter DAC and they're very solid.
They're not going to be everything for everyone, but they are so good to have ready to go, especially for relaxed listening. I couldn't get past the mid and upper treble bite of the Sundara, and I'm not averse to bright tunings. Vocal timbre was not ideal either.
@jasswolf: Everyone's preferences will be different, and it is hard to predict what you will like. I did not think I enjoyed treble very much, but when I got the Sundara I realised that a really enjoyed the treble and precision they offer.
@jasswolf: Some reviewers say that they enjoy the 6XX more with tube amps. But I can't be bothered putting even more stuff on my desk.
While most agree that HifiMan's sound good/better.
Thier build quality and customer service is sub-par
https://www.headphonesty.com/2023/04/reddit-thread-roast-hif…
https://audiosciencereview.com/forum/index.php?threads/hifim…
Focal Clear OG B-Stock for $799 (no issues, cosmetic or otherwise for mine) at Addicted 2 Audio may be another choice in this price bracket.
Does Focal still charge a couple hundred for replacement earcups though?
Yeah, although have heard good things about aftermarket pads.
Can also take a look at some of the refurbished options on the Sennheiser website
LOL my $90 Bayerdynamic (Ozbargain deal) still hold strong.
When you realise most headphones are made of plastic and magnets, you start to realise that high-end headphones are extremely overpriced.
Similar could be said of high end just about anything. There's a diminishing returns curve that kicks in for just about any product class.
It's the same for painting and art in general, people buy feeling LOL
Yeah, I was just reading about the Hermès Birkin handbag the other day (the actress it was named after had recently passed away) and it's really just a handmade leather bag, and a somewhat ordinary one in my opinion (but I'm a guy so what do I know…)
Diminishing returns hit really hard after $500+
the build quality on my hifiman arya's is truly shocking. Extremely cheap feeling plastics, fake leather and the internal wiring job made me think it was some cheap aliexpress knock off toy.
Lines up with my hifiman experience too
This is part of the long list of common complaints about Hifiman. Complaints are so common and consistent that I'm not going to spend money to compare them against anything else- the company has a terrible track record. But Sennheiser build quality has been uniformly excellent. Except for the 800S where the paint is too delicate :/
Even my cheap and cheerful 25HDs are plasticky but still give the impression of indestructiblity. They're been tossed unprotected into airline carry ons and dragged all over the world.
Reductionist and simplistic POV.
Povo
I own a set of hd650's among others.
hd600 series are a fantastic ENTRY level headphones, with outstanding build quality and a great buy for around $300. At $800 HARD no.
I'd be looking at B-stock/used Focal clears for that price. Although I would probably settle on a pair of Meze 99 classics (thats a lot of headphone for $500).
B-stock Clears should definitely be a consideration, as should the HIFIMAN Edition XS and the Ananda Nano, but some people seek different technical and tonal qualities in their headphones, and the S2 actually do some things in a competitive way up in that $700-$1200 bracket, they're just tonally wonky and don't drive for a wide soundstage.
In all honestly, if Sennheiser can fix the tonal balance (can be done these days through passive DSP if required) and get the manufacturing costs down over time, this will probably superseed the rest of the 600 series line-up.
HIFIMAN, Audeze, and others are racing towards that big leap in mid-fi, so I'm happy to see Sennheiser's consumer division are also trying to compete under new management.
as a side comment. I'm guessing you haven't ever owned a pair of HIFIMAN headphones. Any recommendation of them should be followed swiftly after by a warning about their build quality and reliability.
The market low end for open-back headphones is the KOSS line-up, starting at around $30. You can get a HIFIMAN HE400SE for as low as $80 imported, which I would argue is previous mid-fi moving into the budget category.
The X2HR is more cheap trick than true mid-fi.
I'm guessing you haven't ever owned a pair of HIFIMAN headphones. Any recommendation of them should be followed swiftly after by a warning about their build quality and reliability.
I've owned two, still currently own one. Sundara had to be replaced due to drivers not being fully phased matched, but the replacement worked great. Edition XS is a little loose on the fit than what most are used to, but it brought a variant of a $1000 headphone down to $550 while improve some technical aspects of it, and it was designed around performing well whether or not you had a good seal. I don't expect incredible wiring and cabling, and I expect the rate of faults and issues with drivers to be between 1.5-3%, because planar drivers are really, really, really difficult to match.
Their changes with headphone design have made them seem cheaper/plasticky, but also lighter and more comfortable for most people, particularly women.
Moving away from that, a really important thing to consider is how people review and follow-up in their commentary on products when they are dissatisfied, and the nature of their issues when they are. Most people, most of the time, will only jump up and say anything to query an issue or complain, and most of the time the nature of their issue reflects that they were either not using the product as intended, or they had the wrong expectations around the product.
The HIFIMAN commentary reflects the fault rates of the drivers, and that there may be the odd machine fitting issue with the headband or enclosure. HIFIMAN's support staff is geared to readily and happily address this, you just have to bother to test your headphones for audio issues and check there's no drama with glue or screws, and even then the latter is likely fixable with a few turns of a screwdriver.
So aside from people being ignorant about planar driver matching, the real issue is that you're reading comments from the US, UK, and Australia, all of which dabble in forms of - mostly casual - racism towards the Asian community. This stuff isn't 'cheap Chinese crap', though nor is it the most premium build quality you can expect. It's good value for money, and it's a well-established company that happily supports customers and listens to feedback.
I get accused of being an audio snob on here quite a bit, and I feel pretty confident in saying such people should direct their ire at you instead. I also find it hilarious that you uphold the build quality of the 6XX (flimsy resin design with minimal foam) and Philips line up (long Hong Kong owned now) by comparison.
Premium materials do not make a premium product inherently, it's what the researchers and engineers are doing that matters more. Both cost money, and you're seeing what a brand new Sennheiser mid-fi product costs today. It will drop in price over time, and they will also release a tuning update if they get good feedback. The only thing the 660 S2 shares with the 600 and 650 is the external elements… the driver is a different make, and even that is vastly different from the original 660.
It should cost more initially, that's normal.
@jasswolf: i didn't know the planar drivers are hard to match. I have a set of hifiman arya's that died within 2 weeks of me owning them, I'm 6months in trying to get them to warranty claim them. I bought them direct and not from an Australian reseller (bad choice)
I knew at the time I shouldn't have bought them, I'd had a very bad experience with Hifiman before. A set of HE400i's which also died within a few months and I had to fight for a warranty claim. Arya's just sounded so good, exactly what I was looking for.
My plan with the Arya's was to buy a left hand driver to replace the dead one. Hopefully Hifiman will sell me one as the driver is unable to be repaired.
I'll be frank my experience with Hifiman has killed headphone audio for me haha. They are by far and a way the most expensive headphones i've ever bought. my end game set. So yes I'm very biased against them, and its not from a place of racism as you put it. That was a (profanity) load of money.
"uphold the build quality of the 6XX" i said I owned the HD650's which were some of the most durable headphones i've ever owned. I've not seen or touched the 6xx's personally. I would have hoped that the base headband and cup design wouldn't be degraded too drastically. but I'm speculating. They look cheap and they are very likely cheap shit designed to hit a price margin which is too high imo.
I can also claim the build quality of their other headphones are pretty good. hd580's hd700's the hd800's and so. I wouldn't recommend them to anyone. The only great sounding sennheiser 'audio' i've heard are the ie900's, which are just insanely overpriced.
I digress. build quality in the high end headphone market is a real problem. I think we both can agree that the hd660s2 shouldn't be high on anyones list of headphones to buy.
I'm really glade you had a great time with your Hifimans. They would be my favorite headhpone company, by a huge margin if… reliability. I know I'm an extremely small sample size. But is it not easy to find a hifiman customer which has a bad story to tell?
@jake93s: If this was AliExpress, their customer support will help you with a full refund, you just have to get through to an agent (type 'bad bot') and explain the situation, and they'll see you've been claiming since the 2nd week you received them. They'll escalate it and give you a refund based on video evidence. Also, did you rule out the driver didn't need to be re-soldered?
And to be clear, wasn't accusing you of thinking that way re: HIFIMAN, simply part of what sustains the public opinion. HE400i pre-2020 was a headphone that did have some build quality issues, and that's the origin of the reputation.
I honestly think a more tonally balanced version of the 660 S2 would blow the market wide open. HIFIMAN are in a very similar spot right now with the Ananda Nano, which is apparently dangerously close to bringing their $3000-$5000 USD options to the $500 USD price point.
But is it not easy to find a hifiman customer which has a bad story to tell?
Sure but when you combine sales figures with fault rates being naturally 2-3x, it explains itself.
https://www.rtings.com/headphones/tools/compare/hifiman-edit…
Our Verdict
The HiFiMan Edition XS are better audiophile headphones than the Sennheiser HD 660S2.