Is there a way to reduce vibrations on these "meh" cans?
Sure I could go without the amp but where's the bass in that? Ha
Each to its own I guess, I like this sensation when listening to hardstyle with my bassheavy cans, getting feedback and not just hearing it makes it that extra exciting (also I use it to know when mastering hardstyle tracks to measure that the bass levels are on a suitable level, when there's very faint of that sensation going on I know it's on the perfect level as typically all great retail tracks provide me that sensation). I'm surprised a HD439 is able to pull that off but maybe that's one of the bassheavy Sennheisers I didn't know of because you need quite some boost in bass before that starts happening, I'm using Q40 + ZO and I need it boosted with ZO in order to start it happening even if the Q40 on its own has like 8dB bass boost but I guess I also listen at very low volume (I use a fixed volume with the ZO amp maxed and Windows vol set to 14%).
I know what you are explaining, when the bass pressure gets too high, you get a sort of ear-tickling experience. It's like an invisible sound you just feel. I feel it all the time but I like it though. :P
Just EQ down the bass if it disturbs you.
You could get in there , make sure the drivers are bonded to the baffle by gluing them around the seam ( where they seat into ) and mass load the shell where you can. Either with Newplast/plasticine or various thicknesses of Dynamat and see how that goes. Would be best to cover the shiny Dynamat surface with the thin adhesive felt ( ~!-2mm thick ) to stop extra reflections.( ~ $1 at Michaels' Craft stores for that felt )
Also if possible cover the baffle ( earside ) with Dynamat leaving a hole for the driver obviously and also cover that with thin felt again. Mass load the back of the baffle with Newplast or equivalent if you can at all.
Sometimes people also add a circle of the Dynamat to the rear of the driver magnet, assuming there are no vent holes in that also, but making sure to keep them clear if so.
Basically you can try to mass load the entire thing it might help. It'll be a bit of a project but not that difficult at all.
Just an idea and I take no responsibility for any mods that don't work out :)