Audio Physic Virgo III break in time?

I bough a used pair of Virgo III's about six months ago. I assumed they were broken in already, but I believe I am hearing them open up quite a bit. Does anyone know the break in time for these speakers?

There might be material applied to the inside of the mid range cones in order to dampen them.

Hard material cones (ceramic and metallic) have a greater tendency to ring like a bell (=distortion) than fibrous paper cones or fabrics . Paper and fabrics can be more easily embedded with viscous damping fluids/materials or weaved in a manner to reduce this form of distortion.

If you suspect a change in the timbre as "open up quite a bit" suggests then you might want to visually inspect the drivers (take them out to see if anything is detached)