In reply to:

Unfortunately the noise I'm getting is purely wind rush noise. There is actually zero perceptible mechanical noise from the fan itself.



I am not doubting you :-) But I'd be really surprised if the direct fan contact with the can isn't at least amplifying the wind rush sound and introducing a small amount of mechanical noise.

Another idea is to reduce the speed of the fan, as it probably doesn't need to be going full bore (if I remember the specs of the fan) in order to do a decent job of cooling the unit. Plopping the appropriate resistor in there would do the trick.

Anyway, thanks for blazing the trail -- I will install a fan sometime soon and post my results.

Cheers,
rjf&