In-Ear Fidelity

The Pad Wear Update (Ranking List Update)

Table of Contents

Chapter 1: HD6X0

It’s no secret that pads can make a massive difference in headphones. To the point where the pad choice alone during a headphone’s R&D can be a make or break point, and unlike cables or burn-in… pads really can “fix” a headphone. Up to a certain point, of course.

But if pad differences can change the sound of a headphone, what happens when the original pads themselves degrade and so differ from their original out-of-the-box condition?

And a few days ago my worst suspicions were confirmed: the HD600 and HD650 that I initially ranked were rather old and so had very well-used pads. And given the significance of the HD6X0 as a reference for many (whether as a common data point or as “the headphone measurement benchmark”), it’s imperative that I address these findings right away and clear up any confusion before they get out of hand.

To begin I present Exhibit A: a picture of worn HD6X0 pads versus fresh ones.

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Look at that, the fresh pads are a good 50% taller (and firmer) than the well-used pads! With such drastic differences in pad dimensions after some pad burn-in, you would think that the listening experience would also be affected just as drastically. And you’d be right.

Behold, the same Sennheiser HD650 (2020 production model), just swapped between the old and new pads:

Comparison courtesy of the Graph Comparison Tool

Yes, that is a 10dB(!) difference at 5kHz, with an overall decrease in upper treble response (>10kHz) averaging 5~10dB and a small decrease in bass response (<300Hz). Granted this comparison was normalised at 500Hz so as to match as much frequencies as possible, but subjectively this more-or-less demonstrates the effects of pad wear on the HD650: the treble takes a nosedive and the HD650 becomes a really dark headphone.

But why does this matter now?

The problem here is that without having looked or touched fresh HD6X0 pads before (or simply forgetting the feel of fresh pads after months of gradual wear), you probably wouldn’t even be aware that these worn pads were far flatter and squishier than fresh pads. But while some may argue that listening (and measuring) with worn pads aren’t representative of a headphone’s real-world usage scenarios, that isn’t quite true, is it? After all, you could probably find a sizable population of HD6X0 owners who haven’t replaced their pads since getting their headphones years ago.

The other problem?

HD6X0 samples with worn pads

While the HD650 is typically described as slightly darker and/or has more mid-bass than the HD600, pad wear effectively reduces these characteristic differences. With worn pads on both headphones, they sound… well, far similar than when compared with fresh pads. And I guess that’s where the confusion around my initial rankings came about; on worn pads, I had classified them as “basically the same headphone”, which got many riled up and questioning my ears.

HD6X0 samples with fresh pads

On fresh pads, the story is a little different. The HD650 sounds more… well, HD650 fans hate this word but I have to say it anyways: the HD650 sounds more veiled than the HD600. Warmer, smoother, whatever your choice of descriptor may be, the HD650 (to my own ears) also sound a little more blunted and rounded around its notes.

The HD600 on the other hand is a little clearer and surprisingly has slightly better imaging as well. I’d still consider it as “average” for an open-back, mind you, but at the very least it’s not the “closed-back tier” level than the HD650 seems to have.

So here are the changes to be made to the Ranking List:

ModelTone Grade changesTechnical Grade changesOld overall rankNew overall rank
Sennheiser HD650No change (A+)No change (B)B+B+
Sennheiser HD600No change (A+)B to B+B+A-

Chapter 2: SR-Lambdas

I have a love-hate relationship with Stax. On one hand, electrostatic headphones are absolutely some of the most technical and resolving cans I’ve ever heard to date, surpassing basically every traditional dynamic driver and planar headphone. And I’m saying this as kind of a planar (or at least, Hifiman’s planar) fanboy.

On the other hand… at times it does seem like nobody knows how to properly tune an electrostat. Warwick Acoustics kind of succeeded, but for whatever reason (most likely because of liberal DSP usage) their Sonoma Model One headphone is probably the least electrostat-sounding electrostat I’ve had the pleasure to listen to, almost bordering on a sluggish planar-like timbre.

For a while, I believed that the Stax SR-L700 was the big anomaly in the Stax lineup, possessing a tonality that surpasses even the relatively well-received SR-007:

I was actually this close to buying this exact SR-L700 unit. Unfortunately it had some issues with the pad clips (fasteners? I don’t know what exactly went wrong) so it was sent back to the distributor to be repaired and then sold to me.

Now, the L700 was successfully repaired and the pads replaced with a pristine pair. But unfortunately…

EUGH. That can’t be right. But that’s the thing, this is the right one. After all, it was technically broken… perhaps the L700 pads were worn out in just right way to fix its originally wonky tonality?

Fresh vs worn/broken pads
"Optimal sample" comparison

Yeah… looking at the additional sample I managed to measure (and also oratory1990’s data), looks like post-repair first-sample L700 is the “correct” L700. A real shame.

L500 unit/pad wear variation
L300 unit variation

Gathering more samples of the L300 and L500 just to rule out any further discrepancies, now it looks like the SR-Lambdas also require a reshuffle in the rankings.

ModelTone Grade changesTechnical Grade changesOld overall rankNew overall rank
Stax SR-L300No change (A-)S- to A+AA-
Stax SR-L500A- to B-No change (S-)AB
Stax SR-L700A to C+No change (S-)AB-


Apart from being a changelog, I also wanted to formally address the effects of pad wear (or pad broken-ness, in the case of the SR-L700) on a headphone’s final sound. But it does raise the question: how can one identify the extent of pad wear outside of extreme outliers? Are “pristine units” more representative than “well-used” units? If so, why do people keep telling me to burn-in headphones before reviewing?

Honestly I have no answer nor solutions to those questions; I guess those are the hidden caveats that need to be considered when referring to demo units available to the public. It’s not like companies are chomping at the bit to send me fresh, pristine units for review, especially when I have hundreds upon hundreds of headphones in the queue already.

For now I’ll just keep doing what I do best: listening and measuring. As per usual I’m just one guy on the internet, don’t take the rankings too seriously.

Support me on Patreon to get access to tentative ranks, the exclusive “Clubhouse” Discord server and/or access to the Premium Graph Comparison Tool! My usual thanks to all my current supporters and shoutouts to my big money boys:



6 thoughts on “The Pad Wear Update (Ranking List Update)”

  1. Why the downgrade on the L300s technical performance? Did the second unit not perform as well as the first one in that regard?
    Thanks for your hard work 🙂

  2. I just wanted to say that you can buy Sennheiser pads from Aliexpress for under 10 bucks. They sound the same. 50$ for a small velour pad is way too overpriced.

  3. And this is precisely why I rock HD600s with worn out pads that are approx. 5 years old at this point, haha— they sound grand and aren’t likely to need pad replacement on a regular basis as HD650s may. I do feel the baffle foam disintegrating could use addressing, but on the whole this is a rather excellent general purpose headphone sans bass quality & extension.

  4. You should also compare original pads to cheap ebay/AliExpress pads. Always wondered if it actually makes a difference.

  5. Yes I agree please compare the aliexpress/ebay pads knock off

    I believe there is one out there that looks almost the same in material.

  6. The graph for hd600 with new pads, hd650 with newpads; looks more similar than
    The graph for hd 600 new pads, hd650 old pads.
    The hd 650 with new pads should sound even more similar to hd 600

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