[brdzuna]

I got my pair of M40x today and they are not quite what I expected them to be.
"Tuned flat for accurate sound monitoring" - not really, these are actually quite bassy and the sound is more V-shaped than flat.
 
I use Shure SRH550 DJ as my main headphones - compared to them the M40x have better build quality and are more comfortable but they lose when it comes to sound quality.
For the ATH the bass is the central instrument and then comes everything else, whereas for the Shures the bass is just one of the instruments that are all equally important and equally represented.
The SRH550 simply have richer, more spacious sound that is well balanced and truly flat, and they cost me about 40 euros less than the M40x.
 
If I notice some changes in sound after a period of burning in, I'll be happy to report it, but I don't really like what I'm getting out of the M40x right now.
Conclusion: the M40x are OK headphones, maybe even great if you are a basshead, but it is hard for me to recommend them to anyone when the Shures SRH550 DJ and SRH440 offer better SQ for less money.

 

[Nizi123]

I got my pair of M40x today and they are not quite what I expected them to be.
"Tuned flat for accurate sound monitoring" - not really, these are actually quite bassy and the sound is more V-shaped than flat.

I use Shure SRH550 DJ as my main headphones - compared to them the M40x have better build quality and are more comfortable but they lose when it comes to sound quality.
For the ATH the bass is the central instrument and then comes everything else, whereas for the Shures the bass is just one of the instruments that are all equally important and equally represented.
The SRH550 simply have richer, more spacious sound that is well balanced and truly flat, and they cost me about 40 euros less than the M40x.

If I notice some changes in sound after a period of burning in, I'll be happy to report it, but I don't really like what I'm getting out of the M40x right now.
Conclusion: the M40x are OK headphones, maybe even great if you are a basshead, but it is hard for me to recommend them to anyone when the Shures SRH550 DJ and SRH440 offer better SQ for less money.

I wouldn't call these a basshead headphones at all. I find they're pretty balanced with no area overpowering another. What you described sounds like the M50x. Then again, it is subjective. I bought mine used so they were most likely burned in but maybe they'll get more balanced after a bit of listening.

 

[brdzuna]

I guess you can say that the M40x sound pretty balanced when comparing them to something like AKG K77 or some similar headphones, but not so much when compared to the SRH440/550.
 
Anyway, I hope the sound clears up and gets a little brighter in a week or two, but I'm not overly optimistic based on what I'm hearing now.
Which is a shame really because the M40x is quite superior to the SRH550 in terms of build quality and comfort, but that doesn't mean much when SQ is not up to my liking.

 

[Mad Max]

  ...Anyway, I hope the sound clears up and gets a little brighter in a week or two, but I'm not overly optimistic based on what I'm hearing now...

 
It will not with the stock pads.

 

[c61746961]

Ditto. However, you may have good results with the HM5 velour pads, they tend to flatten the bass.

 

[LikeABell]

Hello Guys,
 
I've been using these cans for around 6 months now.
I had problems with the treble too, it was just way too harsh initially. But then it settled down beautifully with some hours behind it.
I am pretty satisfied with the M40s. Has plenty of detail and no part of the spectrum is overpowered, its all there.
This is a pair where you'll appreciate the cymbal crashes as well as the bass guitar.  
 
I will be receiving a pair of HD558s(next thread yo!) soon and I'm looking forward to comparing the M40s with them. 
 
PSST: Jimi's 'Little Wing' sounds especially beautiful with the M40s.

 

[metal571]

The only colorations I heard prominently were the mid-bass bump but it's a lot less than the one on the M50, and the treble above 10k is clearly boosted a bit artificially.
 
Jimi's All Along the Watchtower on my K701 is a religious experience for me

 

[Mad Max]

  Hello Guys,
 
I've been using these cans for around 6 months now.
I had problems with the treble too, it was just way too harsh initially. But then it settled down beautifully with some hours behind it.
I am pretty satisfied with the M40s. Has plenty of detail and no part of the spectrum is overpowered, its all there.
This is a pair where you'll appreciate the cymbal crashes as well as the bass guitar.  
 
I will be receiving a pair of HD558s(next thread yo!) soon and I'm looking forward to comparing the M40s with them. 
 
PSST: Jimi's 'Little Wing' sounds especially beautiful with the M40s.

 
558 has good balance, too, apart from higher fidelity.  You'll probably love it.

 

[LikeABell]

   
558 has good balance, too, apart from higher fidelity.  You'll probably love it.

That's good to know.
I'm especially excited about the soundstage since it'll be my first open back headphone.

 

[imran27]

How will the sound of M40x be impacted if I replace stock pads with "Thick HM5 memory foam pads"? I'm not interested in velours for isolation problems. Comfort is an issue with the stock pads, they are rather too shallow for my ears

 

[c61746961]

Not an easy guess, pads 'behave' very differently. Try for yourself!

 

[Nizi123]

  How will the sound of M40x be impacted if I replace stock pads with "Thick HM5 memory foam pads"? I'm not interested in velours for isolation problems. Comfort is an issue with the stock pads, they are rather too shallow for my ears

 
The sound is very slightly impacted, but for the better imo. A little more low end and because of more room, better sound stage. Honestly, the HM5 pads should be a required purchase after buying the M40x, especially if you are having comfort issues. For me it made the M40x go from pretty good to outstanding. 

 

[Ufasas]

If it's 0 soundstage, so how that one guy uses it for cs:go???

 

[Mad Max]

That soundstage remark was a hyperbole.

 

[metal571]

No it really has one of the narrowest soundstage I've ever heard in a headphone. I don't know why anyone would use these for gaming.