HD600 Vs. HD650/6XX Vs. HD660S - Audio - Linus Tech Tips

Arguably the most famous headphone lineup of all time. There isn't a person who knows anything about audio that hasn't heard of the famous Sennheiser HD600 lineup. Now you could argue that this line started in the 500 series with the extremely well regarded HD580 followed by the HD580 Jubilee several years later. Now Sennheiser with the help of Massdrop is reviving that line with the HD58X Jubilee (review on those in the coming months). But today I'm here to talk about the 600 lineup which consists of the HD600, HD650, HD6XX, and HD660S. Today I will be shooting out the 600, 6XX, and 660S and letting you all know which one is superior and which one you should buy. I'm also going to talk about the future of the 600 series lineup and how it might not be around much longer. Without further ado let's start things off with the HD600.

 

 

Sennheiser HD600 $286:

 

 

The HD600 first came out in 1997. It is one of the most legendary headphones of all time and even 21 years later they are one of the highest regarded on the market and still highly recommended and used by many people. They have gone through slight tweaking over the years, but still the base technology is quite old. Don't let the numbers full you, there are some headphone lines where the numbers don't mean anything for how good they are and this is one of those cases,

 

Build:

I'm only really going to do this segment on this headphone because all three of these are more or less build the same, I'm only going to describe their differences in their respected sections. These are one of the most legendary headphones of all time, they are built well. In classic Sennheiser fair all the materials used feel nice and high quality. The plastics feel high quality and there is a nice feeling piece spring steel making up the headband. The pads are very large, what I would call a 4 finger pad (meaning you can put 4 fingers of a fist in the hole of the pad), and the head cushioning is very supple and soft. The entire package just feels very well built and solid. Not any foldablity so not good for portable use. Now as for the finish on the plastic the HD600 and HD650 have a glossy finish, where the HD6XX and HD660S have a matte finish. Also, the HD600 has an incredibly ugly quail egg color scheme. This is why you see a lot of people paint their HD600 because they are quite ugly. (Build: 8/10)

 

Comfort:

These are among the more comfortable headphones I've ever worn, once you fix the major problem. All of the HD600 series are known for a stupidly strong clamp force. I can tell you right out of the box these clamp like crazy. It's almost to the point where it hurts and it feels like it's cutting off blood flow to your face. On the upside these will never fall off your head. For any of you who are Air Force fighter pilots and want to replace your standard headset with any of these, go right ahead they will not fall off your head no matter what kind of maneuvers you do. In order to fix this clamp force you have to open the headband up all the way and bend the metal and it massively reduces the clamp to the point where they are very comfortable. Don't get me wrong they still have a strong clamp, but they are actually very comfortable now, and they still won't fall off. Plus with the combination of the large velour pads, and soft head cushion, these are a headphone that I have no problem wearing for long hours. Also of note these are pretty deep so you won't have to worry about your ear hitting the drivers which is always a huge plus. Now the HD600 are going to loose a point over the HD6XX and HD660S for me personally. The head cushion of the 600s uses the 4 bump style that the 580s used. The 650 later changed that to 2 larger bumps more on the side of your head and nothing on the top. This is personal preference. I know people who like the 4 bumps more than the 2 and have swapped the cushions in their 650s with the 600 one and likewise I know people who 650 head cushion swapped their 600s. This one is up to use, but I prefer the 2. The 4 starts to hurt on the top of my head after about an hour. Also of note is that the pads on the 600s use a different type of velour than do the 6XX and 660S. The pads are also curiously thinner and cut with a different rake angle which doesn't help the comfort any. (Comfort: 7/10)

 

Misc, Power, Wires, and Accessories:

The stock cable the 600s come with is terrible. It is way to thin and janky and is way too long at 10ft. It also uses on of the strangest 1/4in adapters I've ever seen. Also the connectors are recessed farther than any other Sennheiser connector I've seen. This is an unusable cable in my opinion because it is too long for a desk and is just a really crappy cable. I will link a cheap and better replacement, and Periapt for a higher end option. All 3 of these headphones come in the same really nice hinged box with a foam insert. As for power these are 300ohm and fairly hard to drive. Of note these seem a bit easier to push than the 650s. Also for all 3 these are open back and they leak a good bit of sound.

 

 

Sound:

While you can tell that the 600, 650, and 660S are from the same family of headphones they all have their differences. The 600 is the most different of the 3 without question. That by no means makes them bad,

 

Mid Range:

Mids on these headphones I would classify as exceptional. The 600 has a bump in the mids that the 650 and 660S doesn't. Some would classify them as "shouty" but I quite like them. While testing the 3 there were songs where I started with the 600s and then went to the 650 and 660S and though my volume was too low because the vocals were so much quieter, but that wasn't the case it was simply the more vocal forward nature of the 600. And the quality is incredible. These are some of the best vocals in a headphone in my opinion. (Mid Range: 8/10)

 

Treble:

Treble on these is also spectacular. Very clear and crisp with a good sparkle. These have more treble than the 650 does, and don't quite so much of that famed Sennheiser veil. Strings in anything sound really good and very accurate. (Treble Amount: 6/10) (Treble Quality: 8/10) 

 

Bass:

If you love bass, these are not a headphone for you. These have some of the lightest bass of any headphone I've used. Now it is not non-existent, these aren't a Grado headphone, but it still ins't much. That being said, the bass that is produced is very tight and accurate. (Bass: Amount 4/10) (Bass Quality: 7/10)

 

Sound Stage:

These are on the narrow side. Not insanely narrow, but still pretty low sound stage which is important in a bit. (Sound Stage 4/10)

 

Imaging:

These image very well. Lower sound stage typically helps with imaging and that seems to be the case here. While stuff isn't far away sounding, it can be easily pinpointed. Still not T50 MK3s, but very good. (Imaging: 7/10)

 

Gaming:

These headphones suck at gaming. As many of you know I divide gaming into two categories, fun and competitive. These are not good at either. No bass and sound stage to be good a fun gaming and too narrow for competitive. While you also may recall I said sound stage wasn't important for gaming, that is only true to a degree. If it is too narrow then it does hurt footstep reproduction. Then there are those of you who will point out that I say the T50s are the best competitive headphones and they are as narrow or narrower. While that is true, remember the T50s are god when it comes to imaging, so that makes up for it. If the 600s had a bit more sound stage I think they would actually be good competitive headphones because they have so little low end gunshots won't drown out the footsteps. (Fun Gaming: 2/10) (Competitive Gaming: 4/10)

 

Tubes and Balanced:

The HD600 is the most tubed headphone of all time. Everyone will always tell you that 600s need to be tubed, and indeed they sound much better on tubes for music. There is an added width and added low end that really helps them out and they are spectacular. The Schiit Valhalla 2 would be my choice of Amps for the 600s. We can debate if balanced makes a difference or if it is just an thing with the balanced section of the Amp being better quality, but regardless these are one of the headphones that I think changed on balanced and for good. Slightly more width.

 

Sennheisr HD650/6XX $367:

 

These are a headphone that probably need no introduction. The HD650 first came to be back in 2003, but I will be using the HD6XX for this showdown. The HD6XX came to be back in 2016 when Massdrop collaborated with Sennheiser to make the legendary $500 HD650s be able to be sold for $200. Many people question the build and sound quality becasue it seems too good to be true, but there are only a few differences. 1. They are midnight blue instead of gunmetal grey like the HD650s. 2. They have a matte finish unlike the glossy on the HD650s. 3. They have a 6ft cable that terminates in a 3.5mm instead of a 10ft cable that terminates in a 1/4in on the 650s. That's it, there is nothing else that is different with these from the HD650s. I have the 6XX for this review, but note that if you have 650s they are identical in build and sound.

 

Build:

Same as the HD600 but with a matte finish and slightly different pads as mentioned before. (Build: 8/10)

 

Comfort:

Slightly more comfortable than the 600 for me because I like the two bumps over the four. Also as mentioned before deeper pads than the 600 with a softer velour. Once you fix the clamp these are still some of the most comfortable headphones I've used. (Comfort 8/10)

 

Misc, Power, Wires, and Accessories:

As for other thoughts, the stock cable these come with is okay. It's a 6ft cable that terminates in a 3.5mm jack (with a 1/4in adapter included), and it works. I could live with it if I had to. Same nice box as the other 3. As for how hard they are to drive, they aren't that hard. People freak out with these because they are 300ohm, but honestly they don't require a ton of power. Out of the 3 though these are the hardest to push. Your phone will push them, not to their full potential, but it will push them. Not that you'd probably want to use them with your phone because these are open back headphones and they leak sound like crazy. Everyone around you can hear exactly what you are listening to. 

 

Mid Range:

 The vocals are a bit recessed compared to the 600, but they are still spectacular. They are super crisp and clear and never get lost despite them being slightly recessed. These headphones do vocals well for those of you who like music that is vocal centered. (Mid Range: 7/10) 

 

Treble:

 As for the amount, these are not treble heavy headphones which is why they are so easy to listen to for a long time. However that doesn't mean the treble is bad. The treble is very smooth and relaxing. There is this crispness and sparkle to the treble that is simply amazing These headphones excel at classic music. If you are one of those people who likes to kick back and relax listening to classic music these are the headphone for you. (Treble Amount: 5/10) (Treble Quality: 8/10)

 

Bass:

This is the one category where the 6XXs do not shine. These are not bassy headphones, there's nothing else you can say. Now they do have bass, these are not HD600s where the bass barely exists, but for bass heads these are not what you are going to want. In fact I actually dislike listening to bassy hip hop or rap music with these. Could I listen to deadmau5 with these? Yes, but they wouldn't be my first pick for EDM. Now the bass itself is very tight and focused, and it has what I would describe as a booming sound, even though there isn't much of it.  They don't have bad bass just not much (Bass Amount: 5/10) (Bass Quality: 7/10)

 

Sound stage:

These headphones have sound stage, but not a ton. Are they wider than M50Xs? Yes. Are they Fidelio X1/X2 wide? Not even close. Personally not having a super wide sound stage doesn't bother me, I just need some. And they have more than the 600s for sure. (Sound stage: 5/10)

 

Imaging:

As for imaging these are very good. I remember one of the first songs I listened to with these there was someone playing a piano and I remember flipping out when I could hear the difference from left to right of the guy moving up and down the piano. These image very well. (Imaging: 7/10)

 

Gaming:

The 650 isn't enough bass or sound stage for a fun, better than the 600, but not Monoprice Retros. They are passable as a competitive headphone because they have sound stage and good enough imaging for footsteps. Not my top pick for gaming headphone however. (Fun Gaming: 3/10) (Competitive Gaming: 6.5/10)

 

Tubes and Balanced:

The HD650 also really likes tubes. I would say I probably prefer them on tube over solid state, but I don't think you are missing quite as much running them on SS over tube. The 650s already have the width and low end that the 600s don't so the tube doesn't add as much. Tubes seems to add some echo and reverb which is nice and I like the sound because it matches the signature. And once again I think these change on balanced. Little more width and crispness to the highs.

 

Sennheiser HD660S $500:

 

The HD660S is a new edition to the Sennheiser lineup, debuting first back in late 2017. The 660S is slated to be the successor to the HD650, which are some big shoes to fill. There have been rumors that Sennheiser will soon be stopping production on the HD600 and HD650. This would be a massive mistake in my opinion which I will talk about later. The 660S is similar to the HD600 and HD650, but with some noticeable differences. The biggest change is the choice of drive. The HD600 and HD650 more or less use the same driver with some tweaking, a 40mm 300ohm driver. The HD660S uses an extremely modified version of the HD700 driver which is a 38mm 150ohm driver. So the HD660S is running a smaller driver than HD600 and HD650, and for those of you who know headphones using the HD700 driver should scare you because we all know what a horrible headphone the HD700 is. But, I can confirm that Sennheiser fixed all the issues and these are not even close to the HD700. Curiously, the new Massdrop x Sennheiser HD58X Jubilee is also using an extremely tweaked version of the same 38mm HD700 driver. I'm interested to see how much Sennheiser messed with it to where those are worth $350 less than the 660S. The HD660S is a very good headphone as you will soon see, but their biggest issue will be their price tag which I will get to later.

 

 

Build:

These are built closer to the HD6XX than they are to the HD600 and HD650 both with a matte finish, the same pads, and supposedly sharing some more internal parts. There are two big cosmetic areas that make the HD660S stand out from the rest of the 600 series. The first is that there is no longer the big Sennheiser logo on the top of the headband. Instead, Sennheiser moved it down towards the left side of the headband and only put the word "Sennheiser" in a smaller font and removed the S Sennheiser logo. The second thing they did was added a bump of the mesh on outside of the cups and placed a Sennheiser S logo there. Also they added a lip to the back of that mesh. (Build: 8/10)

 

Comfort:

Exactly the same as the HD6XX and HD650. Tight clamp that needs fixed with the same pads and two bump headband. (Comfort: 8/10)

 

Misc, Power, Wires, and Accessories:

Let's start with power. These headphones are very easy to drive being that they are only 150ohm and more efficient than the HD600 and HD650. This makes them actually very suited for portable use. I will talk later about portable use on my iFi portable if you are one of those people that's fine with open headphones in public. Same nice hinged box as the other 3. As for wires these come with 2 wires. The first is the standard 10ft Sennheiser 1/4in cable that comes with the HD650, 10ft cables are always bad IMO. The second is the same 10ft cable, but with a 4.4mm balanced Pentaconn connector. This is a standard that Sony and Sennheisr have been trying to push as the replacement for 2.5mm balanced on portables. Which makes me question why it's a 10ft? I mean, I know why, because Sennheiser makes an new Amp for these that uses the 4.4mm, but still I promise you less than .01% of 660S owners are buying that Amp. I would of much rather seen a traditional 4pin XLR balanced instead of 4.4mm. Also included is a nice 1/4in to 3.5mm adapter that is a short wire and not a solid metal piece (Fostex take notes) since these come with a straight up 1/4in cable and not a 3.5mm on an adapter, I prefer a 3.5mm with a 1/4in adapter.

 

 

Sound:

These are exceptional sounding like the rest. The best way to describe it would be a blend of the HD600 and HD650 with one huge added bonus.

 

Mid Range:

Mids on these headphones are very neutral and sound basically just like the HD650. Very clean and crisp and not forward like the HD600. (Mid Range: 7/10)

 

Treble:

These have around the same amount of treble that HD600 do. Not too much, these aren't treble heavy cans by any means, but the strings are nice and pronounced and sound very good. I think they are a just a tab bit artificial sounding compared to the HD600, but still very nice. (Treble Amount 6/10) (Treble Quality 7.5/10)

 

Bass:

Bass one these sounds pretty much the same as one the 650s if not the tiniest bit more. Not basshead cans, but ample bass with very good quality. (Bass Amount:5/10) (Bass Quality: 7/10)

 

Sound Stage:

Same as the 650s. Not crazy wide, but wide enough for my liking.

 

Imaging:

Oh my god, this is where you are going to want to own these headphones. These headphones are probably tied for the best imaging I've ever heard in a headphone. These are as good as the T50RP MK3s if not better. Sounds are so stupidly precise it is scary. This might be the new king of imaging. The accuracy of where sounds are placed is breathtaking. You can tell every little millimeter of left from right, these are just exceptional. (Imaging: 9.5/10)

 

Gaming:

Not enough bass or sound stage for fun gaming, so that's out. But, competitive gaming oh my god..... These are probably my new favorite gaming headphones for competitive. They have the stupidly perfect imaging of the T50s while having a bit more sound stage. These are once again wall hack headphones because the footsteps are perfect and you can tell exactly where they are coming from. If you are a competitive gamer with some spare income and want to improve your game, buy these. I promise you these are better than any gaming headset or any 7.1 virtual surround. These are the best competitive gaming headphones money can buy. (Fun Gaming: 3/10) (Competitive Gaming: 10/10)

 

Tubes and Balanced:

These don't change that much on tubes because they are quite easy to drive, but there is slight tubey sound that comes out with these and it is enjoyable, you get the pass to tube these. As for balanced I think these change a bit on balanced too.

 

Which One To Buy and Conclusions:

I'm not going to do test tracks like I would normally do with one these showdowns because these headphones are so similar and I don't think a shootout is appropriate. Instead I'm going to explain each of these headphones and where they fall in the market and let you decide which is for you. All my testing was done with 3 Amps, Aune X7S (balanced and unbalanced), a Schiit Valhalla 2 Black, and a Schiit Lyr 2 with Tesla tubes, all were feed by a Schiit Yggdrasil DAC and all tracks listened to were FLAC in either 16/44.1 or 24/96

 

 

Let's start things off with the HD600. These are the most neutral of the group. If you do audio mastering any of these three are perfectly acceptable to use, but the 600s would be my first pick of the 3 for mastering because they are the flattest. If you like a somewhat neutral headphone with a balanced sound these are probably for you. Out of the 3 these push the most detail because they are very close with a narrow sound stage.

 

The HD650 and the HD6XX I think more people would enjoy for a bit more sound stage and low end. They are also somewhat neutral, but not nearly as much as the HD600. The 650s are a bit more laid back and in the age we are now where most people like bass I think these will suite you well. They are also acceptable to game in where the 600s are just a no all around for gaming. The 650 is the most laid back of the 3, not that any of them are particularly intense.

 

Now the HD660S. If you asked me which of the 3 I would pick, I'd take the 660S. They strike a nice balance between the HD650 and HD600 with the 600s sharper highs, and the 650s sound stage, low end, and mid range. Personally though if I could of picked I would of rather of had the HD600's shoutier mids and the HD650's more relaxed highs, but that's just me. And then of course the HD660S has probably the best imaging of any headphone ever and the best competitive gaming can there is in my opinion.

 

I wish it was that simple, but unfortunately the pricing of these 3 is going to complicate things. Now if you look at the current Amazon prices of at the time of this review the HD600 is $286, the HD650 is $367, and the HD660S is $500. And then of course to complicate things further we have the HD6XX for $200 every few months when they are on Massdrop. And then to complicate things even further I tend to like buying lightly used cans on eBay. 

 

So the first question is if the HD650 is worth the $80 more over the HD600? I'm going to say yes if you want that sound signature. The 650 is more comfortable, looks better, and has a better stock cable. Now if you can wait the delivery time, the HD6XX for $200 is going to win this entire thing because that is the best value all around. So now the next question is if the HD660S is worth $500? That's a tough one. Are they worth the cost over the other 2 or 3 depending on how you want to look at it? No, I don't think so. I like the blend of the HD600 and HD650 sound and that imaging is to die for, but the overall sound isn't that much different. And $500 puts them into competition with things like the Hifiman HE560 and the Beyer Dynamics DT1990. I do happen to have a set of HE560s on hand and I would probably take the 660S over the HE560 because of it's cleaner sound sound and better imaging. And also these are an Irish made pair of Sennheisers vs. a Chinese made set of Hifimans. And spoiler alert for my upcoming HE560 review, they break, a lot. As for the 1990, that is much closer. The 1990 is a closer sound with close imaging and much more detail reproduction. Kind of like a more advanced HD600 without quite reaching the level of the HD800. For you Europeans out there I understand that you can find used HD800s for around $500 and for that case you'd be crazy to take the 660S over the HD800. For us Americans we pay almost $900 for used HD800s so that's out of the question.

 

So let's look at eBay prices for all 3 of these headphones. I paid $180 for my pair of HD600s. The guy said he bought them on Amazon, used them for 6 hours, and didn't like the sound signature, so I had to pick them up. A very lightly used pair of HD600 and HD650 can be had around $200 if you are patient and or get lucky with an auction. Then you can get a new set of HD6XXs for $250 all day long if you don't want to wait for Massdrop shipping. I also see new HD600 and HD650 for around $250 on eBay from time to time. I paid $350 for my set of HD660S and they were used about 10 hours and are in perfect shape. I will admit I got a bit lucky because it seems most pairs go around $400 used. Going off of used prices I still don't think the 660S is necessarily worth it. If you have the money and want that imaging, then yes I would take the 660S, and I will say they are the best out of the 3, but they are pricey. I hope that if Sennheiser does discontinue the HD600 and HD650 that they won't base their decision off their MSRP prices. The HD650 retails at $500 and the HD600 retails at $400. I don't think Sennheiser should stop making the HD600, the HD660S is not a fair replacement because it is not as flat and doesn't push the detail that the 600 does. The 600 needs to stay as the serious work can of the 3, at least while on solid state, once again tube them for music. The 660S is a more than worthy successor to the HD650, but I still would be sad to see the 650 go. If they do stop making the HD650 Sennheiser needs to drop the price of the HD660S to $350 then it would be a no brainer, the HD660S would be an obvious pick because they are amazing. In fact they are probably my favorite headphones I own at the moment, they are just simply incredible. I would say to Sennheiser to keep making the HD600, and if they stop with the HD650, keep making the HD6XX, but at that point I think they would still make the HD650 because the only change is the color scheme, but I digress. Then of course we have the old school HD580 which is also a comparable headphone to all of these and those can be found for $100-$150 which makes them a great bargain if you can find them in good shape.

 

Now real quick for portable use, if you are okay with using open headphones in public the 660S is also the best to use portable because they are so much easier to drive. The 660S can be pushed by smaller portables like a Fiio Q1 MK2 no problem. I have an iFi iDSD Nano Black Label which is a decently powerful portable putting out more power than something like an Oppo HA-2, and it will get the HD600 and HD650 going, but you can tell it's just not quite there. The HD660S no problem at all. Speaking of portables, I have a review coming in the next 2-3 weeks of the 1More Triple Driver Over Ears which I bought as my portable headphones. Trust me you don't want to miss that review so stay tuned.

 

Now at the end I'm going to do a collection update. First for the 3 Senneheisers and then for me as a whole as of June 14th, 2018. Starting with the Sennheisers the HD600 I already have sold to my friend who will be using them for his new mastering headphones to replace his HD380 Pros. I really wanted to keep the HD660S, but I can't quite justify spending another $350 when I already have the HD6XXs and they are so close. I cold sell the 6XX and keep the 660S, but once again I will never sell the 6XX because they are the universal reference point I compare everything to. Plus I have the HD800 goal so I need to keep saving up some money. 

 

As for the rest of the collection I am swamped with headphones. I am going to be selling some cans soon and then buying HD800 when they come back down in price a bit. The HD660S, M1060, HE560, and SHP9500S will all be gone in a few weeks and more stuff will be to come.

 

 

Anyway, thanks for reading my review, I hope you found it helpful. I will link everything used below as well as some of my other reviews to check out.

 

HD600

HD650

HD6XX

HD660S

Aune X7S

Schiit Valhalla 2

Schiit Lyr 3 (Because Lyr 2 is no longer made)

Schiit Yggdrasil

Cheap Replacement Cable

Periapt Cables