I love how emotional Tyll gets in this review - really exemplifies his passion for headphones.

*holding on to my 650s for dear life*

And this is why I ALWAYS take Tyll's reviews heavily into consideration when looking for another headphone for a purpose! Honesty is a virtue that a lot of people are starting to lack as years go on but this man still has it! Thanks Tyll for all that you do and for your honesty!

So sad that's Tyll was not in headphone community anymore. I really miss him. His knowledge and honest opinions when reviewing headphones.

As a HD 600 owner, I waited on the HD660s because of so many negative reviews. After I received my "refurb pair" this week, I can tell you I don't know what these guys are hearing. The HD660s is absolutely great. I feel like i've been cheating out of years of possible enjoyment...

I applaud Tyll here for staying true to his ears. He's become somewhat of the black sheep in the headphone community lately, but I think we need those differing opinions that give a point of view that isn't part of the "hype train". It's important to be critical in these matters and is very helpful hearing some possible downsides with this set of cans. As was the case for the Sony Z1R, time will tell if the 660s captures the hearts of the masses.

Speaking as someone who owns both the HD650 and HD660S, I can easily recommend taking this review with a grain of salt. I respect Tyll's opinions on the HD660S, but I found the new sound signature to be a welcome change and a great overall improvement. Also - Sennheiser isn't discontinuing the HD650 anytime soon.

I just gained a lot of respect for Tyll to be able to call out a company like Sennheiser.

Love the honesty. Thanks Tyll

It's a very very bad sign when Santa almost starts crying before Christmas.....

I have both the 650 and 660S. After listening to the 660S for some time and switching to the 650 it feels like something is missing. Everything sounds dull and lifeless after listening. To me to FR sounds about the same between the two, with the 660S being slightly more crisp and impactful because of the faster driver. I personally like them better than the 650.

Wow, this was heart-wrenching. :(

For people that are still wondering about what Tyll's taking about, he is right to some extent. So, the 600 and 650 are indeed smoother sounding headphones because of the drivers, but it's not that the 660S is a grainy headphone, it's just that it's not a forgiving headphone. In my experience I love the 660S because of how detailed and wider they are in comparison (even tho the treble isn't as extended as it should be) but the fact is, I feel exhausted after a while of using the headphone because they have too much detail and texture, it's not grain, just giving you all the flaws there are in the recording. While the 600 and 650 can be heard for hours without issues, losing the detail the 660S has. It's your choice, both are great headphones.

Thought he was going to start crying.

Geez! I'm not sure I've ever watched a YT video and actually "felt" the disappointment like this before, even as he was struggling to recommend it.

I never saw him so disappointed.

I am a fan of Sennheiser, including this series. I own HD580, HD600 (for many years my favorite) HD650 and of course HD660S. According to me, this new model is the best of them all ... provided new pads are replaced with old ones.

Hmm I was waiting for a black Friday sale to replace my over 20 years old 600’s but you make me doubt now. Excellent review!

You are one of the very few that accurately points out sound characteristics as well as strong and weak points of headphones. When testing out different headphones based on your recommendations I´m pleasantly surprised about just how accurate your reviews are. Thanks a lot!

i was waiting for your review, thank you very much for this review. i own a hd650 and was thinking upgrading to hd660s, but after this review, i don't need to upgrade.

Your passion really comes across in your videos

Wow. I was not expecting that. Let’s take a moment of silence for The Legend.

I'm happy I waited on your review before buying. I'll stick with my hd600.

I'm feeling better about not returning my 650HD & "upgrading" to the 660S. I've had my 650HD for a month & love them, but my curiosity had me wondering if the 660S was superior bc of the latest changes made to the headphones. I'll sit tight for now & enjoy my 650HD. Thanks for the honest & informative review👍🏼👍🏼

I've had my old 600 for almost 20 years and they finally broke beyond repair (not the can's fault, it was me being overly stupid). I chose them BECAUSE of their smoothness and now I have to buy new ones. I'm already anxious abouw the "new" version of the HD600 and if it's REALLY E X A C T L Y the same as the old ones while having a peek at the 660S. Back then I chose the 600 over the 650 on purpose. I haven't listened to them yet but I just hope I can get "my" sound back.

This is my favorite Tyl video of all time. He’s so spot on here. It’s disastrous and the legend does not continue.

Thank heavens I just saw this as I was rushing out to grab a pair. I have rescued my 650 from the bin. For all the noise below, the distilled fact for me is that if there is a difference between 650 and 660s, it is so small that an 'upgrade' from 650 doesn't live here.

My HD-6XXs have been getting more and more comfortable using other people’s methods to ease the clamping pressure, but it wasn’t until I bent the headband like Tyll shows at the 2 minute mark (was convinced the plastic would crack 😬) that I achieved nirvana. Thanks Tyll, and enjoy that retirement.

I own both the 660s and 650. Although they both have a very similar sound signature I totally agree with this review. I still prefer the 650. I cant really put my finger on it but somehow its just smoother and more refined.

Would be interesting to hear a review over the HD58x

Great review, the HD600 was my gateway headphone they last so long.

I think the hd 660s are great better than the hd 600 I used to own and I have the 660s.much more clarity better soundstage and sometimes depending on the music cleaner.

I own the 660s and had the 650s as well. The 660s is more capable technically - it's quicker and appears to be more resolving. But it doesn't give me goosebumps. It sounds slightly off and the timbre is slightly metallic and homogeneous. It has a massive dip in the upper treble region, by as much as 10db, so while everything sounds clearer, everything sounds a bit dull and lifeless on these. Like Tyll says, music sounds quite compressed on these. Clear and super resolving but with frequency response of a cassette almost. There's a lot of detail in the midrange and lower treble, then it just dies off. It's still a great headphone and I enjoy them but you're losing some of that natural sound the HD600 and 650 are famous for for some extra detail and clarity.

6:07 - About the Sound Quality

This is absolutely amazing headphone on my Multibit Bifrost + WA2 w/ custom tubes. I've had 650's as my favorite headphones for years, now 660S takes it's place. Not sure where all the negativity comes from. It's amazing allrounder. It's faster, it got more treble/resolution, more holographic sound, better base texture & definition. Just love it. And no it's nothing like HD700, HD700 is absolutely terrible headphone, bought it twice and sold it twice.

Hmm ,shame you never liked them,i think their better than the other 600 range...the 150 ohm impedence is a good thing as most people can only afford Zen Dac's or similar sub £500 headphone DAC's which with the balanced inputs is much better souding than in plain stereo mode...the first bad review of these HD660S's i have seen on KZfaq, everyone else, myself included ,think their far better than the over warm 550's or 600's, and i play bass, i can hear string textures ,string scrapes, fretting and can tell the classic bass's easily...I guess all our ears are different...i luv them....and who wants 600ohm impedence unless you can afford a £1000+ headphone amplifier, my £200 (plus power supply) Zen DAC headphone amp is more than good enough in balanced mode.....

I've owned the 650 for over 10 years now and recently joined the Massdrop 6xx drop just to make sure I will enjoy the beautiful 650 sound for years to come.

Thanks for the review, always look forward to them! I really hope they don't discontinue the 600 or 650.

It's sad going back and watching these reviews and knowing the last person left telling the truth or isn't ignorant in what is important in sound is retired. Tyll is the only one who hasn't misled me in a headphone purchase. Nearly every other somewhat mainstream reviewer has given me at least two regrettable purchases while Tyll remained at zero. Now it seems all we really have for somewhat relevant reviews is Zeos and I have had more purchases sound nothing like he described than ones that do.

I would have been super interested in hearing what he had to say about the 58X.

Back in 2014, I learned about tyll which contributed to me buying the HD 600's in early 2015. I tried 250 ohm dt880's and 400i's, but stayed with the 600's. I had no yearning to buy the 660's, but decided to look them up randomly on here. It seems like he still has his integrity + will enjoy this hobby for the rest of his life. The 580's were one of the "wow" moments for him in headphones, so you can see why he was emotional about these. I definitely value his opinion.

I'm keeping my HD 650 and HD 600 and passing (at least for now) on the HD 660S, although not based just on Tyll's review since I have the HD 700 which he reminded us in this video is "just not a good headphone" to his ears, yet I really love the HD 700.

Two things i'll agree with Tyll on here. One is that the 660 shouldn't be considered a successor. Not because they aren't good enough, but because the 600 and 650 shouldn't be discontinue(if they are). Two, the lack of a cable designed for portable use. It's pretty foolish to advertise that ability while not providing a cable to do so. Outside of that the 660 is simply better than the 650 and 600. I was confused the majority of the time by some his comments, most of which were emphasizing the smoothness or lack of smoothness in the different headphones. While a "creamy" sound is enjoyable, it doesn't mean that the headphone is better. The 660 most certainly has more detail and the imaging is also better. I can't speak on its ability to scale with different amps but there's not much that I can point to that the 660 isn't better at than the 600 & 650.

The sincerity and dedication of Tyll’s video forces great respect.

Subscribed. Thank you for your thorough and honest opinions!

Zeos raved about these things. I'm torn now since Tyll seems to have a completely opposite opinion. My head wants me to trust Zeos, but my wallet wants me to trust Tyll. :(

huge fan... loved your role in the hangover

i went and bought the 660s after seeing zeos and metal571s reviews. I also have the hd600 for quite a while and when i started comparing the two i wasnt really sure if i liked the 660s more or if they where just different. they where clearly the faster headphone specialy in the bass. drums sounded a lot snappier. but there was also something unnatural about them. it was something in the treble that didnt feel totally right. However now that they had some time to burn in (i guess) they really do sound right and i actualy like them more than the 600s now. when i first listen to the 600 and then switch to 660 its like taking of some foam that muffles the sound a little bit. the music seems to have more air between the instruments and therefore sounds more ''fresh". i still like the 600s specialy for vocals but they often make me sleepy cause they are soo relaxed and lean sounding. the 660s are not the opposite of that but for me they are just in the right spot between pumpin and relaxed sounding. i also have the beyerdynamic dt770pro 80 ohms, akg q701 and hd599 and to me the 660s sounds the best out of all of them. i think they are the fastest with the tightest bass which i like. I do like to use eq apo to bring down the midbass just a bit(1 or 2 db) boost subbass by 5db and boost uppermids(3500hz) by 2 db. for me this makes them just that much more balanced.

660s are such good headphones, they are like the hd600, but with much better soundstage. totally diagree with his verdict.

Holy shit I'm so glad I bought a HD-6XX maybe I will get another to add to my collection including my just ordered HD-58X Jubilee

When you got to review headphones at 8 and be Santa Claus at 9

If there are a few 580/600/650 and 660s owners here, just as a quick tip, the Lehmann Linear headphone amp will get the maximum performance from your Sennheisers. It really is a superb sounding headphone amp. I bought my 580's in July 1998 and they are still sounding great.

its the cable!!! OFC cable provides more clarity at expense of perceived shoutiness in vocals and trebles. I just pluged original hd600 cable (red/black conector ) to my hd660 and i am impressed. Smoother hd660 and fatigue free listening for hours.

I have a lesser version, HD58X, but it's also fun to listen. Something interesting is HD58X and HD660S have exactly same sensitivity and impedance. So if your mobile device works well with HD58X, it'll work better with HD660S.

I got my pair of 660 s's two days ago, and I absolutely LOVE them. My audio source is a very good motherboard (AsRock Z390 Phantom 9), a Kiio K3 DAC/Amplifier, using Equalizer Pro as my EQ, and listening to mostly DSD files and streaming high bit-rate audio from Qobuz.com, and man, when all of those things are in place, these headphones sound perfect. The clarity and balance of the sound comes through, even though I like to play with the EQ settings on certain types of songs. Just remember that if you're going to spend several hundred dollars on headphones, your audio source, amplifier, EQ, and file format, are all HUGE factors in the sound. Don't buy these if you're using an older/cheap motherboard, no amp, no EQ, and you're going to listen to lower-quality files like mp3's or streaming from Apple Music or Pandora. Might as well just buy a pair of $50 headphones if you don't want to do all of the other things needed to get the best possible sound out of these.

I'm so glad i saw your video Tyl, I'm going to try out the ones I bought, but probably return them and get to the hd600

A tragedy unfolds

Wow! What a ballsy review?! Well done that man for being (so) honest. If he were a lesser know reviewer, he would now be looking for alternative employment. I am sure the equipment used in his reviews is (probably) more revealing than what we might use with the same headphones, ergo; he can find more of what he's looking for. A damning review just before Christmas too, does this mean I need to stretch for the HD800 S?

660s have way more clarity than other 6 series

Love the straight honesty t y For that, iam listening to you and getting the hd 600s and you hot e new sub right here

Yay ! Inproved earpads for my HD600 !

A tear just fell from my eye. :'( Be strong Tyll, together we can make it through!

You look like a typical resident of the far north, a Siberian. Great review!

In a German review here on youtube the reviewer favoured an X2 over the 650, but he recently did the 660s and that is now his new reference headphone. But only after a serious break-in period. Right out of the box they didn't sound good in the highs.

Thanks very much for this review...as always I just took your advice an ordered the HD 6xx from massdrop for $199.00.

I really want to try these. But for $100 more, I really have my eye on the LCD 2 classic

Thanks for the review! I always respect your opinion. The true test of the headphone should be a hands-on or rather ears-on at a headphone store that can provide a demo.

Wow I really don't hope they discontinu the HD650, it's the best headphone I ever heard! Great review btw!

Next video "Z Review - Sennheiser HD660s (The Best Sennheiser Can.... .)" HAHAHAH XDD

finally! been waiting for this to find out what's the difference between the HD 650, great to hear the honesty in the review..thanks Tyll

I think this headphone would be suited for my applications. I don't use the HD 558 as a portable solution, but do love having it at my desk, without AMP or DAC (since I don't hear any problem that I'm considering getting one). I'm also on a tight budget and will probably be left without being able to get proper AMP/DACs with proper headphones in a very long time. This headphone however makes it (probably) possible for me to use it behind my PC without any other device required that would cost me extra. Maybe if I'm getting older and get a proper income I might actually be able to jump into the "personal end-game". But this headphone, for me, sounds like a perfect "access to high end, at a lower cost for people with a tighter budget". Yes, the headphone might be "expensive", but I won't be needing anything else for some time, yet still have a great sound (though lacking in some aspects compared to the older family members).

Disappointed but will always have my 600s - interesting they decided to discontinue the 650 and not the older 600..

Tyll, has your opinion changed in any aspect on these cans since reviewing? You are the only KZfaq review I have seen that did not think these we superior over the 600 and 650. I have always valued your reviews and that is why I am asking if you have any review changes on these. In my opinion you are always spot on. Thanks in advance for the reply!

Thanks Mark Hammil!

Its almost like hes the doctor who cant find the words--"sorry, she didnt make it"

I really enjoy your measurement and logic/mostly objective reviews. It's a refreshing change from the hi-fi media that overhypes things because they don't want to lose ad revenue, or rabid fanboys that can't seem to ever find anything wrong with the brand. Based on your review, I'd place those cans BELOW my $100 Audio-Technica.

Best headphones. Using them even on my DAP.

Fantastic review! Please keep up the good work!

They get mellower once they break in a bit, including the pads, they are quite stiff out of the box and the drivers are a bit too far from your ears, you can tell a new pair sounds a tad tinny compared to a one used a couple of months.

this is the reason to watch tylls channel. he is the no frills headphone reviewer. his ears are refined and polished from all the testing.

Thank you for your honest opinion.

I am over hear listening to this video in my 660s XD

Waiting for Hifiman's Sundara.... I really want those to be good so they can be my next purchase.

I love my HD650's and did not quite like these 660s. No way i ever sell my pair of HD650.

Thankyou for being honest with this review. I agree with the cable length, too long for portable use anyway.

I think headphone makers these days are torn between designing models for the traditional audiophile and the younger portable device crowd.

Μoment of silence for the 650s everybody. RIP

Thank you for the review. Season's Greetings to you and yours.

Yay great review! Please review the new mayflower arc dac/amp for $200 it directly competes with the Schiit stack

Damn, now I'm just glad I have my HD650s. I hope I don't break them, tempted to buy another reserve pair. They are my fav can hands-down.

Love the rants here, good video review too.. i will stick to hd 650 then..

Amost noone speaks about pioneer monitor10 or old AKG k240df or k260. With slight tuning down the treble to "non damaged hearing" best cans ever. I own all 3 of them. Sometimes when I listenbto the pioneer I wonder where to find real progress in 40 years development...

I listen to mine with balanced cables and bought at adapter. The grainy sound goes away. I promise you. The sound profile resembled the 600 and 650 as though they had a baby. I was disappointed at first also. Another thing. Burn in matters too. I only burned mine in for one day. Hope this helps.

I'll go HD600 all day and any day for the price! No brainer! And yes, scaling! Spend your money upstream! Great review, Rich.

hmm, I wonder how much the new pads (not worn in) of the HD660s effected your impression. I would be worth changing the pads with the worn HD650s and see what happens

I understand Tyll's impression of the HD660s now, I have own them for six months and recently replaced them with HD600, and HD600 is a far superior headphone compared to the 660s.

Great review as always!

Only I got the sense of humor here? Great video that made me laugh and thanks your thoughts on these headphones, I might go for the 650.

i'm on my Massdrop HD 6XX's as i watch this lol. I'd think instead of these at this price point, given everything you've said, try to get the Focal's Massdrop is releasing shortly....

didnt knew old luke skywalker are reviewing headphones now. lol! love your craft tyll!