Since you guys are so good, I'd ike to keep the momentum going...

My theater is going in the basement. I was planning on a nice carpet pad with a berber wall to wall carpet. I am pretty confident that my basement is leak proof, although there have been some filled cracks. Initially I am not planning on heating the basement, but I am relying on heavy insulation. I live in New Hampshire, so this plan may have to be revisited after "beta testing" this winter.

I have heard about some material that resembles tiny egg cartons that can be used under a carpet pad that serves the following purposes:

1. It has air pockets which would allow water & air to flow through. The idea would be that the leaks could dry without serious carpet damage.
2. It would add insulation to the basement
3. It would be "cushier" to walk on
4. It would help the acoustics.

Does anyone know what this stuff is, have an opinion on it, and/or know where I could get it?

Many thanks in advance!