Hi, I had the problem with the Kickstarter Gold Edition, got a new pair from Zolo and now they got lower in volume slowly.
I decided to remove the gold metal filter instead of cleaning with Alkohol. If you do so you will find a second filter layer in black. This combination seems to be the problem:
If for expample you use the Zolos with a small rest of moisture after showering in your ear channel, these two layers of filters will cover any kind of dirt fast.
This fast effect was the reason I thought about an electronic failure.
But after removing the filters both pairs sound great again!
I you leave the channel open there is a risk of damaging the drivers.
These combined filter construction protects the drivers from moisture and dirt, but will always block the sound after a short period of time ...