[MrPhilicorda]

I've been using the m40x for more than a year now and I do like them a lot. I mostly use them at work and when commuting but occasionally I use them for mixing and other studio work, alongside my DT880 & DT811 (and K702 a while back). I don't think they are super neutral/flat/accurate since they have quite a pronounced mid bass hump and a treble spike that can be sibilant in some cases. I experimented with different pads on them and ended up sticking with a pair of Sound Professionals velvet pads. With them I think the bass and treble issues were fixed making them sound like expected for a pair of headphones that are described as "flat". However, with this thread I'm referring to the stock version.

The measurements made by the RTINGS website confirm my impressions showing the mid bass hump and treble spike:
 

 

The other day I popped into a shop that had a pair of m50x so I took the opportunity to do a side by side comparison. I was REALLY surprised with my findings. I was expecting a bloated bass heavy sound because that how people usually describe them, but on the contrary, they had LESS bass. What they did have though, was much better extension in to the lowest frequencies. I could hear kickdrums and bass in a way that I couldn't with the m40x. Gone was the mid bass stuffiness that would mask lower bass frequencies, gone was also that treble spike. I think the whole range sounded more relaxed, and actually, more flat.

Again, the RTINGS measurements illustrate that quite well. The mid bass hump that would be masking the lowest frequencies is gone, treble is also slightly tamed:
 

 
Now I haven't done extensive listening tests. These were first impressions based on maybe 20 minutes and 3 different songs (pop/jazz/easylistening). That was still enough for me to seriously think about purchasing the m50x and continue testing.

Are there more guys on here who have done side by side comparisons with the two? 

 

[MrPhilicorda]

No one has compared the two? For a couple of years now I've been reading over and over again (on Head-Fi and other forums) how the m40x are the accurate/neutral ones and the m50x is the bass monster. My brief A/B test the other day seemed to show the opposite, backed up by some measurements I found..
 
I'm genuinely interested to hear other users impressions, let me hear your thoughts!

 

[Music Alchemist]

I owned the M50x, M40x, and M30x, but at different times. Actually had two pairs of the M50x, also at different times—both had such overwhelming bass that it ruined the sound for me. The M40x and M30x sounded more accurate to me overall. But if you were to reduce the bass of the M50x with EQ, it would probably win.
 
Here's a graph to illustrate how much extra bass it has. (Compare to the green line.)
http://cdn.head-fi.org/2/2b/2bec6adf_Audio_Technica_ATH-M50X.png
http://www.innerfidelity.com/images/AudioTechnicaATHM50x.pdf
 
Unfortunately, InnerFidelity did not measure the other two, so I can't share graphs for those. I'm not sure why the M50x had less bass when you auditioned it. I would recommend comparing at home with familiar music from the same DAC/amp.
 
By the way, the measurements you posted are compensated, not raw. In other words, they're not the actual measurements, but instead showing how they follow an arbitrary curve. Still, it's interesting how the M40x does have more measured bass there. Maybe I should get another one and see how I feel about it after all this time.

 

[MrPhilicorda]

Yeah, I know the measurements I posted are compensated curves, but RTINGS are the only ones AFAIK who have measured both. Now I didn't listen to any songs with lots of deep bass, and if I would have, I might feel differently about the m50x. But it was still rather clear that the m40x has exaggerated mid bass. Much more so than my other headphones. That alone would make me hesitant to stick the flat/neutral/accurate label on them.

 

[Music Alchemist]

Yeah, I know the measurements I posted are compensated curves, but RTINGS are the only ones AFAIK who have measured both. Now I didn't listen to any songs with lots of deep bass, and if I would have, I might feel differently about the m50x. But it was still rather clear that the m40x has exaggerated mid bass. Much more so than my other headphones. That alone would make me hesitant to stick the flat/neutral/accurate label on them.

 
Yeah, definitely not neutral. (This is what neutral sounds like to me.)

 

[MorrisL]

This is a strange thing to read. I do a lot of mixing work and have tried over a dozen headphones to mix with. I finally chose the HD 600 because it was the most neutral of them all. I then started looking for a close back alternative for the HD 600 to be used at nights and when kids are playing at home. I went through many pairs and m40x was the most neutral. I will tell you more... The mixes done on them translate so reliably well that I can just do all my work with that and my laptop and no one would be any wiser. I now trust them even more than the HD600s.