Well, the sound is more liquid, less dry (no pun intended!!), less edgy, less grainy. The change in sound is very noticeable and I really wonder if humidity can alter sound that way, but since I did not do any change in either configuration or placement, it must be related to humidity (it is really hot and humid in Montreal these days and in-house humidity is in between 70 and 80%). I notice the change in sound after the second really humid day, so perhaps the cone paper absorbed some moisture, enough to change the weight and/or stiffness of the cone.
Now, the overall response is not different, HF and LF extensions are the same, but the difference is in the texture of sound and affects frequencies from around 4kHz to 7kHz, wich is good because that's precisely where the FE168EZ has some problems in getting the right balance between definition and smoothness. Now it seems I get both smooth sound without losing definition.
I'm glad because humidity is a real cheap tweak and is very reversible (untill mold gets into the cone...).