Thiel Owners

I will try switching the wires but I like the mechanical explanation because this does only happen during moments of extreme bass like that where the driver is moving an extreme amount.

To diagnose the vibration issue, I should remove the woofer and just look for something loose or would you suggest trying to play that clip while the woofer is unscrewed??

Incidentally, when I turned off the amp and cranked the subwoofers by themselves, I also found vibration noise coming from one of the hanging ceiling panels. I was able to resolve it, but there's no way I would have noticed it if the main speakers had been playing too. 

I don't know if this is of help in tracking down what is going on in your system, but I do not hear the same "flutter/buzz/vibration" sound you hear when I play a Qobuz FLAC file of the Boz Skaggs track on my Thiel 2.2s at moderate volume levels. Perhaps I would hear something if I stressed my speakers at a higher volume level, but I'd rather not push them too hard. 

Yeah that's an interesting data point, thank you.
I only get it on my right speaker so far. The only way I can explain how loud I'm playing is roughly 60db spl as reported by the free decibel x iphone app from 1 meter in front of the speaker. It's louder than I normally play them, but not intolerably loud, even when sitting 1 meter from it.

When I go quieter than that by even a little, the noise doesn't happen. 

I am suggesting that you pull the woofer and snoop around.

will do, thanks!