[GearMe]

IMO, return it.

1. It might be a fake if you didn't buy it from an authorised seller.
2. You just don't like the sound and that's completely fine.

If your first impression is that "I do not like this", return it if you can. Don't try to fix it, or get your ears tuned to it.

First impressions are very important, and there are likely better suited headphones for you out there. We all like different things and that's completely fine.

I did this...

Got my first HD660 from Amazon -- Sennheiser HD 660 S - HiRes Audiophile Open Back Headphone (Renewed) for $256.50. Was happy with the price and that they were 'Manufacturer Renewed'

The bass sounded wonky as well, so I returned them.

Since they were 'Manufacturer Renewed', I thought they'd 'sound like new'. Because of this, it took me a while to get comfortable with reordering. Once I did reorder, it was a new-in-the-box purchase for me at $399. Very satisfied with my replacement pair.

That said, @Blackfyre has a very valid point. You may not like these...or the the Senn HD600 line...sound signature. Trust your ears!

 

[Luckyleo]

This is my first post here.

First thank you to everybody for all the posts about your impressions of the HD660s. I needed a headphone and came to lurk on these pages for an opinion and I found very valuable guidance for my purchase.

About a month ago I finally ordered an HD660s from B and H and it arrived yesterday. It took so long due to my living in a remote country.
Why the 660? Because it has a slightly higher sensitivity than the other 600 series. It comes with a balanced cable, so I thought that I can use it directly with my DAP without additional gear.

The headphones are used with a Sony NW WM1A and its balanced output. Since I have never owned any headphone, but some very fancy setup with high-end loudspeakers and tube electronics in older times I was quite impatient to hear how these headphones would sound. For clarification, I listen mainly to classical music.

Here is my opinion after listening a few hours to them with FLAC files either 44.1/16 96/24 or 192/24.

My first impression out of the box was that the sound was extremely bloated in the lower frequencies, obscuring details in the mids. It produces a very unpleasant, chaotic and inaccurate sound when listening to symphonic music with a high dynamic range. It seems like the headphone is limited in its dynamics.
The mids and highs are reasonably clean and detailed (when they are not overwhelmed by the lower frequencies). Not extremely detailed but OK.

The bass bloating is so overwhelming that I had to throttle down that area with the built-in equalizer. But even then, something does not sound right. Bass drums sound awful and inaccurate. Some loud symphonic passages with a lot of low frequencies sound just chaotic rumbling. It’s not music anymore.

There is also a very nasty distortion in the higher mid range when it gets louder. Very bad sound. Maybe it is coming from the configuration of my ears, or the DAP. I don’t know. It’s odd.

The sound sorely lacks space and air for classical music. Everything is in my face.

Generally speaking it is not a bad product. I hear glimpses of very clear and transparent music. For chamber music with limited dynamics it’s quite fine. Actually very nice and engaging. For larger orchestras it is a non starter, at least not for this combination.

Acoustic music with few instruments, Jazz, Blues, etc sounds great. The detailing is very good and accurate although I have a little issue with the timbre of the instruments. They don’t sound exactly the way they should.

They are also quite unforgiving. A bad recording sounds very bad, but I suppose that this is the case with all better headphones.

Now that said, maybe my ears don’t like to be fed with sound so close. I don’t really know.
Maybe it is the WM1A showing it’s limits. Very possibly. I have read that the power supplied by the balanced output is rather low. The volume is at 80-85 over max 120.

I also read in some posts that these headphones need some “burn-in” and they get better after 20 hours or so.

After a couple of dozen hours of listening I might post more if my impressions change.

Again, thanks to all of you.

JB

Hey now!

I own the 660s and the Sony DAP you have. That DAP is great on so many levels, but unfortunately, driving the 660s to it's finest is not one of those. If you want the max sound, you would need a more powerful DAP (A&K?) or an entry level desktop system. If the Sony DAP is your only source, please return the 660s if you can.

My opinions only....

Leo

 

[oldlurker]

Hey now!

I own the 660s and the Sony DAP you have. That DAP is great on so many levels, but unfortunately, driving the 660s to it's finest is not one of those. If you want the max sound, you would need a more powerful DAP (A&K?) or an entry level desktop system. If the Sony DAP is your only source, please return the 660s if you can.

My opinions only....

Leo

Hi there and thank you for your comments.

It has been a few days now since I received my HD660S and I have used it quite a lot.
Here are my notes.

1. It seems that the chaotic rumbling in the bass area has subsided a bit. Is it the headphone, is it my ears, I don’t know. It could also be the DAP getting burned-in, since I have never used its balanced output.

2. The bass is still too dominating for my taste and I apply a slight downwards slope of equalization from 500Hz down. It helps a lot by clearing up the bass and lower mid area and allows me to hear the individual instruments. The sound does not feel bloated anymore.

3. The kind of ringing that leads to distortion in the upper mids has been fixed by slightly equalizing down around 6-8kHz. This produces a much cleaner sound in the mids. No more nasty ringing. Unfortunately, I cannot do this very finely since the DAP has only 10 eq. bands.

The result now is that the 660 is a more pleasant piece of gear. It sounds very polished, very civilized. No harshness whatsoever. Very detailed, but not excessively. It’s like a good Bordeaux.
Maybe a bit too polished and sometimes lacking adrenaline, but I suspect this is due to the pairing with the Sony DAP which already delivers a very smooth and polished sound.

It still lacks dynamics and space. Some loud symphonic passages are definitely very challenging for the drivers and it is a pain to listen to. But maybe it’s due to my DAP which does not provide enough headroom.
But for well recorded chamber music which has a small number of instruments and a smaller room it is truly a nice headphone.

The timbres also sound more accurate now.

I noticed that the sort of “veil” which is often mentioned in relation to another member of the 600 series is noticed by me on the 660 as well on certain recordings. It is a bit strange. The sound feels like being behind a curtain. The instruments don’t seem to be really present. Nice presentation, but not there.
Maybe the 660 renders accurately what is in the file. I don’t know. But it is a very strange effect which remembers me gently that I am listening to “canned” music after all.

Of course, besides the bass rumbling issue and the ringing which am very certain of, this is all very subjective, especially since I do not have any way to compare with other devices and I am using only one source. I only have in-ears, but my ears are allergic to them.

The 660 in their current version are very comfortable headphones and this is surprising given the number of people complaining about the high clamping force. Not at all, and I have a very big head.
I can wear them for hours without any trouble or discomfort.
The construction seems to be first rate and well thought out.

Given my location which makes it very difficult to listen to before buying and to return anything, I will use patience and possibly buy some amplifier. But then there is the issue of the source. The NW1A does not have a line output. Use the headphone output to feed the amp? Or buy a dock, a DAC and an amp…
I bought this to be transportable and easily powered by 12V batteries.

Edit and update: after more listening, the upper mids and the low treble are just not clean. I tried everything with equalizing and there is still quite a bit of distortion producing a kind of ringing, especially at higher sound levels.


@ alexeyi
I also thought about the 800s, but that is a step too far at this time.

@ Blackfyre
I am pretty sure it is not a fake. Bought from B and H which is an authorized reseller. The build of the headphone really looks genuine. Unfortunately the QR check on the Sennheiser website does not seem to work anymore.
It’s not that I don’t like it. It has some major flaws out of the box.

@ kman1211
Yes, it works very well with small formations. It seems to loose control with large and loud orchestras. Yes, maybe it’s the wrong product for me. But then, which one and how do I check if it works? I would need to fly to Singapore or the US...

@ SHAMuuu
Thank you for your comments. Yes, the 660 is at ease with pretty much every genre.

@ cummje
Yes, I will be patient and see how they evolve over time.

@ GearMe
It’s not that I don’t like the sound. Some complex orchestral pieces just don’t play well. No way to return them.

@ Luckyleo
It’s OK, I will think about remedies. But I don’t want to be taken in the never ending pursuit of a unicorn… LOL

 

[457139]

I think the 660s sounds amazing with the Walkman One firmware on the WM1A. It's pretty addicting honestly

 

[Luckyleo]

I think the 660s sounds amazing with the Walkman One firmware on the WM1A. It's pretty addicting honestly

Thank you! Appreciate your thoughts. However, I say this out of curiosity only, please don't be offended, but what setup are you comparing the sound of the Walkman to?

 

[457139]

Thank you! Appreciate your thoughts. However, I say this out of curiosity only, please don't be offended, but what setup are you comparing the sound of the Walkman to?

Didn't actually compare it to my Earmen Tradutto/Geshelli E2 combo, which I am selling coincidentally haha. I was more or less sharing thoughts on the 660s/WM1A combo on it's own merits

 

[Fvizeu]

If you think the 660S sounds a bit muffled or veiled, I have the solution. Not kidding. Just remove the foam between the drivers and your ears and everything opens up. Also, don't forget to replace the foam with a very thin fabric to keep the drivers protected. I'll attach some pictures of my unit.

I'm a huge HD600 fan and always disliked the HD6XX/650 sound because they just sound too muffled for my taste. When I bought the 660S, I had an appreciation for the improvements it brought to the 600 line but part of me thought it had a small resemblance to the 650 on that regard.

But when I removed the foam, they started to sound like the upgrade I always expected for the HD600. Do yourself a favour and try this. Hope it helps

 

[jonathan c]

I already did the same and more on HD6XX & HD600: clarity abounds!

 

[Blackfyre]

I already did the same and more on HD6XX & HD600: clarity abounds!

What's that metal looking piece you have at the back of the driver? Acoustically what do these changes actually do?

Ideally if there are any measurements in terms of frequency response graph changes for before and after, that would be great.

 

[jonathan c]

What's that metal looking piece you have at the back of the driver? Acoustically what do these changes actually do?

Ideally if there are any measurements in terms of frequency response graph changes for before and after, that would be great.

Custom Cans UK modifications. Go to: jfunk.org for details.

 

[Fvizeu]

Custom Cans UK modifications. Go to: jfunk.org for details.

https://jfunk.org/wpc/product-categ...rvice/headphone-damping-mods/sennheiser-mods/

Bought mine yesterday. Hope it sounds good, but it's a cool idea.

**It doesn't work for the HD660S, as far as I know. I bought it for my HD600.

 

[Malfunkt]

these are the ones.

I’ve owned HD800, 650, 600, 700, 630VB, 540, 250, 25, Amperior. Enjoyed them all.

My main set for the past few years was a Focal Utopia - which were incredible. However, I prefer the presentation of the 660S. For spatial DSP and binaural use - this is among the best spherical soundstage representations. This headphone is future proofed and will serve well into the VR / AR gen of media. Enjoying this right now using dts-x via nPlayer Pro on iOS.

This driver is excellent. Comfort and design are the business. Sounds incredible even off an ios lightning-dongle!

Waited since 2017 to get these. Owned a set of 650s back then and I feel like I’ve come back home. But this is a very different headphone.

Sennheiser’s best imo (though I haven’t owned HD820 or HD800S and not counting the HE exclusives).

So much music to enjoy again. Everything is so addictively good with this set but not over-sweetened.

 

[SHAMuuu]

these are the ones.

I’ve owned HD800, 650, 600, 700, 630VB, 540, 250, 25, Amperior. Enjoyed them all.

My main set for the past few years was a Focal Utopia - which were incredible. However, I prefer the presentation of the 660S. For spatial DSP and binaural use - this is among the best spherical soundstage representations. This headphone is future proofed and will serve well into the VR / AR gen of media. Enjoying this right now using dts-x via nPlayer Pro on iOS.

This driver is excellent. Comfort and design are the business. Sounds incredible even off an ios lightning-dongle!

Waited since 2017 to get these. Owned a set of 650s back then and I feel like I’ve come back home. But this is a very different headphone.

Sennheiser’s best imo (though I haven’t owned HD820 or HD800S and not counting the HE exclusives).

So much music to enjoy again. Everything is so addictively good with this set but not over-sweetened.

That takes some guts to make such a bold statement to the Focal King.

I think they are superb and stylish and comfortable (rare combo)

Is this in combo with the 02/odac?

 

[Malfunkt]

That takes some guts to make such a bold statement to the Focal King.

I think they are superb and stylish and comfortable (rare combo)

Is this in combo with the 02/odac?

I've been mostly using them right out of the Apple dongle, as well as via my MacBook Pro M1 (which has an excellent headphone out). I've had the 02/ODAC for years, and found no reason to upgrade/replace it - it has gobs of solid state power - way more than needed for the 660S.

Regarding the Utopia - an exemplary headphone - if not one of the very best. But in terms of overall enjoyment and complete package - the 660S suits my current tastes and needs more.

 

[SHAMuuu]

I've been mostly using them right out of the Apple dongle, as well as via my MacBook Pro M1 (which has an excellent headphone out). I've had the 02/ODAC for years, and found no reason to upgrade/replace it - it has gobs of solid state power - way more than needed for the 660S.

Regarding the Utopia - an exemplary headphone - if not one of the very best. But in terms of overall enjoyment and complete package - the 660S suits my current tastes and needs more.

I guess you're most fortunate you've found something with great overall enjoyment.

Since the majority still seem to lean / favor the 300ohm versions (including 580), the 660s can be had for a bargain.

So I guess that is good news for those who like them, and the fact they don't need a super chain to get optimum fidelity.

I was quite surprised they can sing with a simple dongle dac/amp (e.g helm bolt) to equal levels as the 300ohm brother paired with a beefy tube amp.