[Marximus]

I'm not sure how long they were on the speaker while it was on, but I'm using them now after that incident, and it sounds like the bass was sucked out.  I had them equalized to Treble Booster previously, and they sounded great, but with Treble Booster now, it sounds like their soul was taken.  Even with no equalization, it sounds like it's lacking bass (from what I remember prior to the incident).  Is this a case of psychoacoustics?  Did they somehow get burned in a bunch?  Did I screw them up somehow?

 

[Marximus]

And.....it sounds like the bass in my D5000s got sucked out, too, so apparently it's not the speaker issue.

 

[olor1n]

Were the pads deformed in any way? Perhaps your cans no longer seal as well.

 

[Marximus]

But I'm having the same issue with the Denons, and they haven't ever been stretched out, let alone on a speaker.  It's really weird.  Through all my headphone outs (on the uDAC, the E9, and my Denon receiver) they sound bass-light.  I did go shooting today, but I was wearing earplugs, and I'm pretty sensitive to loud noises, so I would've known if they weren't in the ear properly.

 

[wind016]

I think your ears became desensitized in the shooting range. Just give it a day and the bass will probably come back. This happens to me too after a 6 hour drive from Santa Barbara to San Francisco.

 

[RPGWiZaRD]

A less tight clamp usually results in less bass, on most headphones I try I get more bass if pushing even gently on the cups. Even when not stretching out headphones they still (well most) gets a loosened clamping force with use, some more than others. But if it happened suddenly with the D5000 then that's probably not the cause and more likely the shooting as suggested even if wearing ear-protection.
 
Another tip if you can't simply wait that long then listen to a basslight headphone temporarely and then switch back, that always does the trick for me when I forget how bassy my own ones are.