Comparing the HD600 and the HD580: In Pursuit of the Truth

Introduction

It's no secret that Sennheiser's midrange HD6X0 line (consisting of the HD600, HD6XX/650, and HD580) is likely the most beloved product line in the headphone world. The primary claim to fame comes from their timbral qualities, with their scalability a secondary but not insignificant contributor their supposed sonic prowess. The topic of today's article will focus on the first point. More specifically, the tonal differences between the HD600 and HD580.

In Antdroid's review here, he talks a bit about the resurgence in popularity of the HD580 which led him to investigate for himself what the hype was all about. I've similarly been quite curious about it myself but unfortunately, HD580's are few and far between. Thankfully, someone kindly lent me the HD580 to bring home for do a direct A/B comparison between these two headphones. More specifically, I will be comparing a silver screen HD600 and a black silk HD580 (the same as Antdroid). Yes, not only are there three different HD6X0 headphones, there are different types of internal baffles. I'm far from well-read on this subject though so I will leave it at that and focus on what I have at hand.

Caveats

I do want to preface this article with a few caveats.

1. My silver screen HD600 has quite worn in pads on them compared to the HD580 that I've borrowed. The HD580's pads are newer and thus a lot firmer and don't flatten so easily. This will, of course, have some impact on the sound quality and frequency response. Perceptually, the HD600 is closer to my ears due to the flatter pads which will also affect how I feel about it. I briefly tried to use the same set of pads with both however that didn't work out very well from a practical standpoint. Too much time was lost between swapping pads for A/Bing. Plus, I didn't want to accidentally break the borrowed HD580s somehow.
2. I mentioned scalability above: I will state upfront that I am rather source agnostic. I tested these headphones on both a Burson Conductor Performance 3 (on loan courtesy of headphones.com) and a JDS Atom + Khadas Tone board setup. I didn't hear any differences between the two but as I understand it, both of these solid-state setups are subpar sources to take advantage of the HD6X0's scalability. Thus for simplicity's sake, I won't talk any more about scalability or sources here. This is a relative review after all unless either headphone somehow pulls ahead on X amp vs. the other.
3. These headphones are NOT perfectly volume matched. As in, I got them as close as what I could reasonably get with my ear but I did not use any sort of objective method to ensure the gains were identical.

Sound Differences

On a technical level, the HD600 and HD580 are almost identical. Same-ish soundstage, same-ish resolution, same-ish note separation, you get the idea. I say almost because there are some differences that manifest as part of their timbral/tonal differences that I'll get into. At any rate, suffice it to say that the "legendary" HD580 doesn't actually improve significantly upon what you already get with the HD600. In a lot of ways, this is to be expected given the lineage of these headphones. 

On a tonal level, there is a meaningful difference. The HD580 sounds lighter, with more upper mids presence to it to make it feel more open and alive despite having the same soundstage. Or to put it another way, the HD600 sounds dull in comparison. It's actually something I've suspected for a while now but comparing with the HD580 has finally confirmed it in my mind. One possibility is due to how worn the pads are but in any event, the HD600 lacks a certain sense of excitement in music despite sounding tonally correct. It sounds dampened. Though I'm tempted, I won't say "Sennheiser veil". To me, that implies a dark, smothered tonality where the HD600 is not.

The increased upper mids openness on the HD580 is definitely something I prefer over the HD600. I don't think it negatively affects timbre. If anything, it improves vocals to give them more "breathiness" and air. Similarly, there is an upper treble bump that makes the HD580 sharper and more crisp than the HD600 on hats/cymbals. I really do appreciate this difference because to my ear, it's more natural to real life where percussions are rarely tamed.

EQing

Alright, since I like the HD580 more, it's time to cut to the chase. Let's do some EQ. To get my HD600 sounding very close to the HD580, I only needed to add two bands:

1. +1.5 dB at 2,500 Hz with a Q = 0.5
2. +1 dB at 11,000 Hz with a Q = 1.41

That's it. It's not perfect and in absence of a measurement rig, I can't verify how accurate it truly is but to my ears, it is close enough for me. Try it for yourself even if you don't have a HD580 and let me know what you think!

As for how I got these values, I primarily worked off a rock track, an acoustic track, and an instrumental piano piece. I initially had a minor cut at 150 Hz but after quite a bit of testing, I realized it wasn't necessary for the upper mids clarity in the rock track and actually diminished some of the bass impact in the strumming of the acoustic guitar on acoustic tracks. The boost at 2.5 kHz I had initially split up into two smaller bands, at 2 kHz and 4 kHz. However, when comparing to the HD580, it was too much upper mids and lost some of the warmth and body in the vocals. Combining them and giving it a low Q achieved the vocal tone I was looking for. Finally, the 11 kHz bump is to specifically emulate the sharp/crispness of the HD580 in the hats/cymbals and give the HD600 more treble brilliance.

Validating the EQ

I mentioned the EQ is not perfect, so what are the differences? From a tuning standpoint, it's extremely close. Maybe if I spent a few more hours I might be able to realllllly dial in the EQ across my entire library but I think I'll probably end up going back and forth with adjustments and ultimately end up at a very similar place so I'll save my sanity.

On the intangibles side however, I do think the HD580 has a bit more of a fluidity to it. A certain je ne sais quoi that I wasn't able to easily reproduce. It's not so much a warmth or body in the lower mids. There's like a... connectedness between notes that join them together to better flow into each other. Almost like there's a hint of reverb or the sustain pedal of a piano subtly in effect. Yet at the same time, the HD580 still sounds lighter and more effortless than the EQ'd HD600. The transients are a little tighter and there's more of a staccato effect. Drier perhaps? That said however, I can see some liking the EQ'd HD600 more for a smoother presentation and lengthened decay. From a technical perspective, I'm tempted to say the HD580 has just a little more dynamic ability and mayyyyyybe slightly better imaging. But honestly, this may be a result of a few factors that I'll get into below. 

Caveats Discussion

The most important caveat I want to address here is the difference in the comfort/pads. The newer pads on the HD580 is definitely a different feeling when listening to it compared to the HD600. The newer pads adds more distance for the drivers to the ears compared to the flattened pads of the HD600. While I'm not sure if it truly makes any difference, I can't help but believe that how close the drivers are to my ears would somehow affect my perception of audio. The HD580 is also lighter with less clamp force which may unconsciously influence how I perceive it to be more effortless sounding.

As a follow-up to that, it is possible that the HD580 is slightly easier to drive than the HD600. A minor 0.5 - 1 dB volume difference might be enough for me to prefer it or believe that it has better dynamics. After all, it only took about 1 - 2 dB of EQing for me to bring the HD600 close to the HD580.

The other thing I should address is the variations in the HD6X0 line. Established measurements demonstrate a meaningful degree of variation between various units of these headphones, so much so that it is not impossible for the frequency response of these headphones to overlap one another. Much of these variations come from the state of the pads and the positioning of the measurement rig (or head). Thus, the conclusions of this article should really only be limited to the two units I have in front of me with the current state of their pads. At the same time however, I do see my impressions line up quite similarly with Antdroid's review and I did find that I consistently enjoyed the HD580 more than my HD600 every time I A/B'd it regardless of minor variations in head positioning. Take for that what you will.

Which Do I Prefer?

Before I crown a winner, I do want to heavily stress that these headphones sound very similar to each other. We're talking about fractions of a difference here. While I'm pretty confident I could pass a blind test between them if they were in the same enclosure, there is a tiny part of me that says maybe I can't. 

When I first sat down to write this article almost two months ago, I wrote:

"Although I would take the HD580 today over my EQ'd HD600, this opinion may not be true a month from now. Reviews are a snapshot in time, filled with the biases and constraints of a reviewer's mental state and the limited time they've spent with the gear. It's possible that after a month of listening to the EQ'd HD600 I might prefer its slightly smoother, less dry presentation. It's possible the novelty of the HD580 draws me towards it for the time being. These two headphones are so close that I think it can swing one way or the other. Though I doubt I will revert back to preferring the stock HD600.

Regardless, of the headphones I have in front of me, I prefer the HD580. It just fits my preferences the best. The EQ'd HD600 gets close, very, very close but when A/Bing I would still take the HD580. The regular HD600, despite only 1 - 2 dB of difference overall, is a (relatively) distant second. Just a couple of small EQ bands were enough to bring the HD600 to life."

But a month later, I revisited the topic and compared them once again. This time, I found that both headphones were honestly equally good. Their performance is dependent on the genre and vocalist. Female vocals have a slight edginess on the HD580 where the HD600 benefits from its smoothness. However, the clarity of the HD580 allows for male vocals to better stand out. The drier, cleaner sound of the HD580 favors busy rock tracks while the relaxed nature of the HD600 creates musicality for slower acoustic pop tracks.

Ultimately, I'd still probably give the win to the HD580 by an infinitesimally small margin. The majority of music that I listen to falls under rock or a similar genre which is where the HD580 has a minor advantage. Plus, I just prefer its comfort better - it's lighter and the cups aren't so close to my ears. But I don't own the HD580 so I will continue to happily enjoy the HD600.

Timbre

I do want to come back to the raison d'etre of these headphones. Timbre. That is pretty much the defining reason for their enthusiastic following. Supposedly the HD6X0 line-up of headphones has the best timbre of all headphones in existence. But what is timbre? Or more specifically, what do audiophiles mean when they talk about timbre? Is it "accurate to the recording"? "Sounds like real instruments"? "Natural"? "Just right"? I think with the proliferation of digitally generated music and the ubiquity of significant DSP, the argument for timbre sounding like "real instruments" that are "natural" and "accurate to the recording" is becoming less applicable. Not to mention the roll-off in the subbass would effectively disqualify the HD6X0 from ever being a 100% accurate.

Of course, this isn't to say timbre is a useless term. I don't think any reasonable person would disagree that a headphone with -10 dB in the upper mids and +15 dB in the bass is obviously timbrally challenged by any definition of the word. Rather, I mean to say that when we look at two headphones that both sound very good, what makes one have a better timbre than another? In absence of a rigorous, universally agreed upon audiophile definition, we can only settle for the frustratingly ambiguous Goldilocks description of "just right". And in that sense, the HD580 and my EQ'd HD600 do sound very, very right to me. Moreso than the almost every other headphone I've heard.

One Step Closer to the Truth?

Like most things in life, the truth is somewhere in the middle. Frankly, I didn't know what to expect when I started this effort to compare the HD580 and HD600. There's a lot of mysticism around these headphones that muddies the waters. Add in all the sources of variations from the baffles to the pads and you have a recipe for uncertainty. As you can see from my discussion on the caveats, there are a lot of questions still to but likely won't be answered. Further still is the world of sources to be explored, even if my prior attempts at testing have failed to yield significant results.

For my part, I wanted to at least have a chance to try both of these myself and come to my own conclusions. Based on my experience here, the HD580 is a preferable sidegrade over the HD600 but doesn't change how I would recommend the HD6X0 series against other headphones in the market. But I'm very glad to have had the chance to do this side-by-side comparison. I used to reserve the HD600's as a reference point for headphone reviews but now, with a little bit of EQ, I think I'll be reaching for them more often than not.