Your refering about the bombeat wx-1 right?
I dont know why they made such a long name but yea those lil woofers are amazing but if you plug them to another source you can blow them out .
I have seen another owner replace them with ones that match same color as the grey passsive radiators.
I myself replaced mine long ago with my first model and the sound is surprisingly good because of its design and its tweeter crosover combo.

So you dont have to have exact cones, but you do need a super long screwdriver to open  the box .
I often wondered how it would have sounded if those passive radiators were swapped out for some real speakers.
Anyway goodluck on your search.