I modded it with blutack, and to be honest, I couldn't tell the difference from non-mod. Hifimans measure linear bass in general, but doesn't mean they hit hard.
Blue tack doesn't cut vibrations nearly as well as Dynamat or Sorbothane - its advantage is filling small places and being cheap. Dynamat is cheap as well but because of the metal backing isn't good for every application. Sorbothane is expensive and doesn't stick that well, but it really curbs the vibrations.
If you have a set of HE-500 w/o mods just pop off rear covers, and on the inside edges apply these 3 or any anti vibration solution (not liquid !). Before you do that, locate at least 5 cuts that has bass based on prior experience is too fat or too reverb on the 500. Then put screens back on so u are just testing the anti reverb.
At first I tried all sorbothane, but it was too dead. Eventually I ended up with 3 diff length pieces of Dynamat with gaps. Helps kill the occasionally sloggy bass, but allows vigor and thunder when called for. If you know about bass drivers in cabinets, I'd say the Q went from .95 (sloggy) down to .75-.80 range (.707 is "ideal" - a bit dry IMHO).
The ratio of the spaces and pieces is roughly: pieces 1.7", 1.1", .7" with gaps 1X, 1X, 1X.
My hierarchy of mods:
1. fuzzor - I've waxed ecstatic before in this thread.
2. pads (my testing says Ether Angled are the best) + rear screens off (they both help release the other).
2b. digital parametric EQ.
3. get rid of stock cable in place of DIY/cheap cable set for most current out of your amp (SE vs balanced) 22 or 24 ga, pure copper, good dielectric.
4. the mod described here.
5. Lighter headband
6. Keep away from cooking fumes.
Summary: some trouble and cost, but excepting the HE-6se at $699 I don't know anything under $1k that touches them. Certainly the Ananda is no match for them. The Arya is better.