Used this on all my floorwedges and two subs. Bought two rolls, enough for 10 monitors and two subs!
I also bought spray adhesive, wich did not look pretty at all, it looked like spiderweb. So i ended up not using spray adhesive. I will instead paint the inside of the steel grills and press the foam firmly into place, with some books to keep it down while the paint dries.
Always test on a small piece before doing the whole thing, paint and foam can have a chemical reaction, especially strong paints like polyurethane.
The sound is not affected much. I had some hiss in my floor wedges, and not they are less hissy. But vocals are still crisp and clear