If you landed here from another query, don’t fret. I decided to combine the articles into 1 and cover all of the products in question: Sennheiser’s HD 600, 650, and 6XX vs. AKG’s K701, 702, and 712.
So let’s dive in!
All specs, box contents, and pricing toward the end!
Greetings mate, and Welcome aboard! Stuart Charles here, HomeStudioBasics.com helping YOU make sound decisions leading to a beautiful audio experience that will make you fall in love with music (NOT gear), all over again, so…
Build
The HD Series headphones are a tad heavier at 260g vs. 235 for the K712/K701/K702, but by and large, you’ll notice that they feel roughly the same in your hand.
K series headphones are a bit bulkier overall, while the Sennheiser’s look and feel more compact both visually and on your head.
All have detachable cables, but Sennheiser uses a proprietary variety while the K series opts for Mini-XLR.
I haven’t had a single issue with any AKG or Sennheiser model that I’ve ever tried or owned.
- For a complete list, go here: Headphone Reviews & Comparisons
Both have very soft velour padding that tends to flatten out over time, but each is shaped differently.
The K series is a perfect circle vs. the oval shape of Sennheisers. The cups are both easy to remove as well.
The HD600’s cups kind of snap into place after a gentle push, while the K series rotates and clicks in with about a 1/4″ turn.
I would plan on investing in replacement pads for all 3 down the road, depending on how often you use them.
None fold up and are mostly meant for studio use.
Materials
The K series is mostly plastic with velour pads, while the HD series contains a mix of Velour, Plastic, Metal Grilles, and Carbon Fiber.
I will say that Sennheiser headphones are incredibly durable, but AKG is no slouch here either.
The only issue I’ve had with my K702 is the small piece of clear plastic near the inside of the bale snapping, but this piece is fairly inconsequential and hasn’t had a negative effect on fitment or build.
Additionally, I’ve dropped my HD600 countless times since 2016, and it comes out unscathed every time.
What’s more, the cable, while it looks and feels rather cheap, is anything but.
I’ve run over this thing hundreds of times with my computer chair and it hasn’t a single scratch, blemish, or dent.
It’s simply unbelievable how much abuse the headphones can take.
I can’t say much about the 712 or 701’s cable as I don’t own them, but I do own a 702.
I found that its cable is a lot less durable and rugged. I’ve owned it since December 2019 and some dents and digs have certainly formed over the years.
Thankfully this doesn’t affect the sound, but it’s something to keep in mind if you’re a bit rough and tough with your gear as I am.
Comfort
The comfort of all of these headphones is phenomenal.
Sennheiser clamping force is known to be pretty tight but does open up the more you use them.
I’ve owned an HD600 since 2016 and I still find it hugs my head rather snugly (do keep in mind I don’t use it every single day).
- Required Reading: Sennheiser HD600 Review [With Video]
The catch is that I really enjoy that sense of intimacy.
Putting an HD600 on your head to me feels like a warm hug from an old friend. It’s a security blanket of sorts.
It’s like hugging your boo and knowing she’s looking over your shoulder – but only because she’s got your back.
A K712 is incredibly comfy as well, but it does sit looser on your noggin.
Some people will inevitably prefer this type of fit, and I can’t argue with them.
My SHP9500 is similar in that don’t really feel it at all. It’s almost like wearing air.
The 712 isn’t quite as free, but it’s getting there.
I’d say clamping force in order from tightest to loosest would go something like,
- HD Series
- K Series
- SHP9500
By and large,
you’ll find all of these rather comfy, with a good clamp and almost no fatigue.
I’m rarely adjusting either which makes for an easy time listening to music for many hours.
The K712 doesn’t have any padding for the headband, but you won’t miss it.
The HD Series all have padding: the 600s contain the 4 nugget pads vs. the single pad with a crater in the middle on the 650 and 6XX.
Comfort is about the same on all and very good.
The other difference between these headphones is the way they fit; the K Series utilizes the self-adjusting hammock style while the HD Series opts for the traditional click adjustment.
AKG’s hammock style is certainly more convenient when you’re in a hurry, but if you keep Sennheisers the same on either side it isn’t a big deal.
With that, let’s discuss sound.
Sound
- Amp/DACs Used: S.M.S.L SH-9 w/ AudioQuest DragonFly Red, FiiO K5 Pro, and lots more.
- Source(s): Spotify Premium, FLAC
- Official Playlist: Here and Here!
- Albums: Towards the end!
K701 vs. K702
Before we begin, let me just clarify the differences between the K701 and K702
In short, it’s just about the same sound but the K702 has a bit less bass roll-off and extends a little deeper than the K701. That’s it!
Here’s a nice graph illustrating the point:
Courtesy of Headroom.
One of the first things you’ll notice with the K712 is that female vocals seemed to be pushed back/recessed a bit more than the HD Series, but the K702 and K701’s mid-range are mostly perfect.
The “too forward” quality of the 600’s mids can be bothersome at times, and I’ve said as much since I began reviewing and talking about the headphones on the blog and channel.
Additionally, some people have complained that the 702’s mids can also sound too in your face.
The 650 is a bit more like the 712 in this regard. Its mid-range isn’t quite as forward as the HD600’s and tends to sound a bit warmer and laid back overall.
- Related: AKG K712 Review: Who Is It For?
K series headphones will be more open, with a better Soundstage, but it comes at the expense of a somewhat drier overall sound than HD models.
The HD Series sound is more intimate and closer to you.
It feels more immediate and lush, while the K Series goes for the grand, open approach.
This can make it sound a tad looser and flabby by contrast, but you’ll get more out-of-your-head moments with a K Series than you will with an HD Series.
Of course, much of this is dependent on the track in question, as I’ve felt those moments on certain tracks regardless of the headphones I was wearing.
I’ve said over and over in articles and videos that the way a track sounds is largely the result of how it was recorded, mixed, and mastered, and that’s really no different here.
I will say that AKG headphones do tend to kind of exaggerate those effects to where you’re experiencing them much more frequently, so keep that in mind as well.
Bass
You’ll find the bass on the HD Series is tighter and more focused than that of a 712. It also seems to have a bit more thump, and again, feels closer to your ears while the 712’s comes across as a bit more distant.
Additionally, the 712 goes for a much different bass response than the 702 and 701, opting for a gentle rise across most of the low end, and it’s not necessarily a good thing. This is because the crucial regions of 200-300Hz are not scooped as they should be, resulting in some bleed, bloat, and overall flab like someone on a diet of MACKdonald’s and Krispy Kreme.
This is in no way as bad as some cheap consumer trash, but it’s also not the ideal way to construct the bass.
- Check out the best headphones for hip-hop if you’re curious about why this is so incredibly important.
While the K712’s bass kind of gets in the way of the mids, the K701, K702, and HD Series don’t have this issue; instead opting for one of the preferred bass curves: roll-off below 40Hz, some 60-90Hz emphasis, and flat or cut around 200-300Hz.
9th Wonder, in particular, tends to mix his bass lines pretty heavily, so headphones with less-than-ideal low-end response will make it sound too prominent and, at times, sloppy.
For instance, BobbiSoul!! off of Zion II sounds just “OK” through a 712, and a bit better with an HD600/650/6XX and K701/702.
On the 712, you can tell he mixed the bass a bit too heavily and some of the other frequencies struggle to stand out or receive recognition.
Again, pay attention to how the track was recorded, mixed, and mastered – it will tell you much more about how a piece sounds than anything else.
For example, some tracks may be mixed louder and others quieter.
The same volume on your Amp with different songs can vary quite a bit which is important to remember as well.
Treble
Treble is also a bit different here, as the HD series mostly opts for a subdued, somewhat “veiled” high-end; a point of contention among many.
- Required Reading: What is the Sennheiser Veil?
K Series headphones are certainly brighter than Sennheiser, but because AKG opts for a cut around 9-10kHz, they aren’t sibilant. This is incredibly important because it means there’s a good amount of sparkle without the bite.
I think overall, the 600/650’s treble quality is a bit better, more refined, and clearer to the ear. It’s closer to you and more immediate; a running overall theme in this write-up.
John The Blind’s Paranoid is a fine example of a song with heavy treble emphasis and crispy hits after about 1:04.
Sort of like when you’re smoking a J and getting high as a kite while freestyling with your homies.
Not that I ever did that.
Paranoid is also an example of a track that was mixed and mastered almost perfectly.
I actually can’t decide which one sounds better.
The HD Series, makes it sound closer and more intimate, while the K Series does a fantastic job of opening things up and making it sound grand and spacious.
Treble hits on both are fantastic.
I’m not feeling like one headphone is doing a better job of portraying them if I’m being honest.
The main takeaway with the treble is that neither headphone is fatiguing in the slightest and comes across naturally and effortlessly.
Will you need amplification?
Amplification
- HD600: 300 Ohm, 97dB/mW Sensitivity
- HD650: 300 Ohm, 103dB/mW Sensitivity
- HD6XX: 300 Ohm, 103dB/mW Sensitivity
- AKG K701: 62 Ohm, 91dB/mW Sensitivity
- AKG K702: 62 Ohm, 91dB/mW Sensitivity
- AKG K712: 62 Ohm, 84-88dB/mW Sensitivity
Neither the HD600 nor 650 are too hard to drive, but the K712 is incredibly inefficient and does need more current/power from the amp to reach an acceptable listening level.
Some good pairings for each:
- The Best Headphone Amp for the AKG K701 & K702 (also can be applied to the 712)
- Best Headphone Amp for the Sennheiser HD 600 and 650 [Video]
I wouldn’t get too crazy about it as most pairings will sound really good.
I’m personally not a proponent of synergy, scaling, and all that nonsense most of the time.
In some cases, yes, it can help.
For instance, a hip-dac helps to tame the bright nature of the 9500.
And yes, you’ll mostly want to pair warmer headphones with more neutral amps and vice versa.
2 of the same thing usually ends up sounding kind of weird.
But don’t go into it thinking “Oh my God I have to have the exact right pair or else I will never be satisfied.”
Because it’s not like that at all.
Final Verdict
I think we can safely discard headphones like the K712 and 650, both of which have some issues that not everyone wants to talk about. The 712’s issues are the bass around the bloat regions + the mid-range, and the 650 can simply sound a bit overly warm and dull at times.
While I still own an original, made in Ireland HD600 from 2016, you don’t need to spend that much nowadays. An HD6XX is just about the perfect entry-level audiophile headphone, and a K702, with its better Soundstage and airier presentation, perfectly complements it.
It’s interesting to note that out of the new crop of headphones I currently have, I kept the HD600 and K702 because they work so well together.
I can listen to somewhat harder genres with either while using the K702 for mostly Jazz, Classical, Gaming, Film, and Studio Work.
- Required Reading: The Best Studio Headphones For Mixing, Mastering, And Music Production
If you’re interested in where exactly I place the K702 among the 600/700 series, read this: AKG K612 vs. K712 vs. K702 vs. K701 vs. Q701
Recommendations
I would bypass the K712 and go for a K702 as I think it’s a better overall representation of the 700 lineup.
Learn More:
If you’re after the sound of the HD600 but don’t want to pay the higher price, I’d go with a 6XX nowadays.
Learn More:
At A Glance
Sennheiser HD600
Price: Check Amazon! | Check Sweetwater! | Check B&H! | Check eBay!
| Official Review: Here!
In The Box
Sennheiser HD600 Headphones
1/4″ Adapter
Limited 2-Year Warranty (not pictured)
Specs/Graph
Shoutout to Crinacle for the graph.
Specifications
- Type: Open back.
- Fit: Circumaural (over-ear).
- Impedance: 300 ohms.
- Sensitivity: 97 dB/mW.
- Frequency response: 12Hz – 39000 kHz.
- Material: Metal grilles, carbon fiber, velour earpads, plastic
- Color: Speckled blue finish, black.
Sennheiser HD650
Price: Check Amazon! | Check Sweetwater! | Check eBay!
Sennheiser HD 650 Stereo Reference Headphones
Detachable Cable
Stereo 1/4″ to 3.5mm Adapter
Limited 2-Year Warranty
Specs/Graph
Shout out to Crinacle for the graph!
Specifications
- Type: Open back. Closed back vs. Open back headphones.
- Fit: Circumaural.
- Impedance: 300 Ohm. What is Headphone Impedance?
- Sensitivity: 103dB/mW. What is Sensitivity in Headphones?
- Frequency response: 12 – 39000 Hz.
- Material: OFC copper (Kevlar Reinforced), Velour, Plastic.
- Color: Grey and Black metal flake finish.
AKG K702
Price: Check Amazon! | Check Sweetwater! | Check B&H! | Check eBay!
In The Box
K702 Headphone
Detachable Mini-XLR cable
1/4″ Adapter
Warranty Card
Specs/Graph
Credit: Crinacle
- Type: Open back.
- Fit: Circumaural (Over-Ear).
- Frequency response: 10Hz to 39,800 kHz.
- Impedance: 62 Ohms.
- Sensitivity: 91dB/mW.
- Material: Leather headband, plastic, velour padding.
- Color: Midnight Blue/Silver/Grey
- Cable: Detachable Mini-XLR (9.8 ft.)
AKG K712
Price: Check Amazon! | Check Sweetwater! | Check B&H! | Check eBay!
AKG K712 Pro Reference Studio Headphones
Mini XLR Connector Cable
Mini XLR Coiled Cable
Carrying Bag
Limited 2-Year Warranty
Do note: This is a loaner unit lent to me by a good friend Marko from Finland. He wasn’t able to/didn’t have everything to send which is completely fine! The cable and case pictured are aftermarkets as well. 🙂
Specs/Graph
Graph: Crinacle
Specifications
- Type: Open back.
- Color: Black & Orange.
- Fit: Circumaural.
- Frequency response: 10Hz to 39,800 kHz.
- Impedance: 62 Ohms.
- Sensitivity: 84-88dB/mW
- Material: Leather headband, plastic, memory foam.
- Audio Connector to Source: 1/8″ / 3.5mm TRS
- Adapter Included: Yes, 1/4″
- Cable: Detachable Mini-XLR
- Cable Length: 9.8′
- Weight: 8.3 Oz. / 235g
Well, that’s about it for today my friend! I hope you’ve enjoyed this Sennheiser HD600/650/6XX vs. AKG K701/702/712 comparison/shootout and came away with some valuable insight.
If you love what I do here and want to support the blog and channel in a more personal way, check me out on Patreon and discover all the value I have to offer you.
Questions? Comments? Requests? Did I miss the mark on something? Please let me know down below or Contact me!!
Which one of these are you going to purchase? I would love to hear from you. Until next time…
All the best and God bless,
-Stu
6 comments
Nice write up man! Just picked up the K712 Pro / HD660S / HD650. I think I’m sticking with the K712 Pro. After some testing I agree with what your thoughts. However, you’ve made me interested in the K702. The HD660S were the worst out of the bunch by far. I will pick up the Sundara on Sunday as well as the Philips X3 to find an complimentary headset the the K712.
Thanks man! That’s interesting about the HD660S. I haven’t heard it yet. What were your thoughts?
I have the HD660S2, the HD6XX, the HD58X, and the K712 Pro. Personally, I’m finding myself more and more preferring the sound of the K712 Pro. With a bit of EQ in the bass they really slam on electronic and pop music. The soundstage and more “distant” representation of the K712 with the larger and very fast Varimotion drivers really go a long way into making it a more desirable headphone for everyday listening with a proper DAC/Amp. I’m using the Topping DX5 and these things sound sublime out of them. I’ve found the HD660S2 is a bit more resolving in comparison to the HD6XX and K712 but this can come across as a kind of unpleasant artificial edge/bite on certain tracks. With the K712, vocals and overall treble presentation sound more appealing out of the box to me on certain tracks. I know the FR graphs indicate the Senns are the winners here but I actually prefer the presentation of the K712s on certain tracks, particularly when the bass is EQd up a bit but midrange and treble are left unmodified. Oratory’s EQ presets for the Harman curve ruin the K712s completely imho, they destroy what makes the sound signature out of the box so appealing and kind of turn them into a totally different headphones, bass almost disappears. Both the AKG K712s and the Sennheiser HD660S2s sound great out of the box, but I’m coming to prefer the AKGs. May AKGs Austrian roots live on in one of its final headphone designs before acquisition by Harman and Samsung. I own the Chinese-made Massdrop AKG K7XXs too but the quality of the plastic mold and manufacturing tolerances is notably inferior to the AKG 712 Pros made in Slovakia. Get the K712s while you still can for ~$300 on Amazon, folks. Thomann has stopped offering them in Europe at all (they used to be about $250), I fear they are going out of production and Samsung has jacked the price up to $600 for profit-grabbing reasons.
Nice! The K702 is my daily driver when I’m not demoing other stuff. Here are my ramblings on the 600/700 series if you were interested.
Would you be willing to send the 660 for a demo? It’s the only one I haven’t heard. If not, no big deal.
Oh sorry, I didn’t see your comment there, thanks for replying! I’ve changed my mind about the K712s. I have recently acquired a pair of mint (new) condition Austrian K702s in sealed manufacturer’s packaging from 2012 in the eBay find of a lifetime. Originally I thought they sounded thin. I then fit the gel K712 pads from Thomann on them and these are now my daily driver. Much improved bass response without the ugly midrange mud of the K712s. 🙂
https://www.thomannmusic.com/akg_k_712_ear_pad.htm These are worth every penny if you have a K702. Muuuch better comfort and bass response than the stock pads. All the benefits of the K702s with the bass of the K712s basically.
The K712 Pros sound bloated in comparison imho. I am deeply lucky to own one of the last new condition Austrian K702s in existence. These are literally my endgame headphone and I’ve tried many including planars. The K702s even put the Sennheieser HD660S2s to shame with their airy, pinpoint soundstage. I feel like I own a piece of audio history now (AKG stopped making the K702s with high quality assembly/manufacturing processes in Austria circa 2013.) I hope they will last me years to come. I might consider sending in the HD660S2s for measurement but fear that insuring a $600 headphone during shipment will cost me a prohibitive amount of money.
I am very happy with my Austrian K702s though. I drive them through my Topping DX5 DAC/Amp using optical in from the Asus soundcard in my mini workstation PC and they really shine. I really can’t help but marvel at the incredible soundstage, speed, and clarity/definition of the K702s. Forget the K712s, the Austrian K702s with Thomann’s pads (they are different than the actual K712 stock pads, don’t be fooled) are my endgame headphone (yes, I know they are ‘mid-fi’ but I’ve yet to hear anything better out of the box with the new gel pads affixed on the K702.) It seems all the ‘endgame’ headphones come with unbalanced, harsh sound out of the box (HD800, K812 for example) or simply require EQ (looking at you, Audeze) to be listenable. The K702s with the Thomann pads are simply pleasant as they are without modification of EQ parameters.
Love the K702! I use mine for everything but just gamed with them yesterday 🙂 Kind of jealous you got an original Austrian model lol. My Chinese model is holding up incredibly well. I’ve had it since 2019. I personally love the stock sound as it’s super neutral across the board with a great bass response and has just the right amount of presence at 2kHz.
That said, I may consider trying the pads you linked since mine may need a replacement. If you can believe it, they haven’t really flattened out at all! And yeah I wasn’t a huge fan of the 712 although it wasn’t horrible. Just a bit anemic and wooly sounding for my tastes. I felt like it was a bit bloaty and dull.
What you describe is the magic of “old” and “outdated” headphones (according to the masses). Oftentimes they are the ones we should be targeting!!
Your thoughts are almost verbatim my impressions. It never fails to amaze me how much better the 702 is than pretty much 99% of headphones out there. This is kind of what led me to believe that a lot of the stuff nowadays is simply marketing and flavor-of-the-week BS that is never going to end.
I firmly believe there’s a reason headphones like the 7506, HD600, K702 etc. are still sought after today. It’s because they’re great products. I actually have an original made in Ireland HD600 and plan on keeping it forever!