Seal your lips around the dildo, blow it and see if any air leaks out.

 

Ahh, yes now I remember.  If you look in the back of the cup there's another rubber piece that, AFAI can tell seals with this hole when it's all pressed into place, so it's not actually a vent.  Might be one of those situations where the designers left room for tweaking and they wound up sealing it. 

It doesn't really matter though either way.  Either damp the dildo, or get rid of it and damp the cup.  Your method is probably easier but I bet damping the cups gives you bigger soundstage. 

In the end, you still have a flawed headphone. 

I do wonder if you have a more tolerable sounding version. RD had two K550s. One was nastier than the other. The one he had modded was nastier. (And I'm betting if he had modded the less nasty one, it would have yielded some decent results.)  Unfortunately we will never know because a few idiots at HF destroyed RD's pioneering spirit by calling him a retard, not once, but several times in that thread.  Both of us then responded by proceeded to post elephant shitting pix. Which then resulted in a train-wreck. And Curra having to clean up the aisle. And the thread being locked.

So it's entirely possible that your experience was much more pleasant than ours. I had heard sayings that there were some changes, but hadn't seen or heard anything to better substantiate such rumors.

I think this illustrates how the average audiophile does not really know what to do when faced with measurements. In the end, no matter how a headphone measures, if you like the way it sounds, that should really be enough for you. All ears are different (and with circumaural headphones like these, the shape of our earlobes certainly has a larger effect on the sound than with supraaurals and IEMs, not to mention this particular headphone's well documented fit issues) and our hearing and sensitivity to glare in certain bands also varies from person to person. It is entirely possible that I am one of the lucky few with an AKG-certified head and ear shape and this could also account for why I found the K550 to be more pleasant sounding than you lot...

With sound, placebo and bias plays such a huge role - upon seeing a graph that indicates problems with the sound of the K550, it is extremely easy to be biased to start looking for this issue and concentrating on it in our brain. All of a sudden, this perfectly awesome headphone that you've been enjoying for a few months becomes unlistenable because all that we do is look for this issue that has been indicated by a visual graph, ie. the McGurk effect. Most people don't think about these things, don't analyse them and aren't able to step back and realise that measurements are imperfect and that the issue that affects some people might not effect them. After all, they have golden ears and all of a sudden, their self-esteem is threatened by these black magic scientific graphs. This is why audiophiles will then lash out and call people who are brave enough to post their own opinions based on measurements retards. Oh well, such is the nature of this hobby. In the end, I feel that measurements are a very useful, if imperfect, tool for an objective comparison of headphones but how much of this actually translates into listening pleasure is very debatable and this is the point - measurements give some fodder for a (hopefully) constructive conversation about headphones that has the potential of revealing flaws in certain headphone designs - certainly a positive thing for headphone research in general. But yeah, I can see how posting fairly controversial opinions about the K550 (controversial since a significant amount of owners really do enjoy this headphone) resulted in a bunch of butthurt people lashing out