You have a single tc 2k with a bassis and ep2500... ? I would only consider using eq with multiple large subs.
That looks like the older style top assembly, and you have had enough excursion for the surround to stretch tight, over 25 mm for sure. The deformation doesn't look like a very sharp crease. If you are careful, you might consider taking the driver out of the enclosure and seeing if you can massage the creases out a bit with your fingers.
The voice coil didn't bottom on that one, the surround was the limiting factor on the first ones.
It will be fine as long as you don't keep stretching it to the point of the cone bending, and last a long life. If you push it and it keeps bending, it will eventually break.
A forum community dedicated to home theater owners and enthusiasts. Come join the discussion about home audio/video, TVs, projectors, screens, receivers, speakers, projects, DIY’s, product reviews, accessories, classifieds, and more!