I spent all last night assembling the GR research AV1's. There was no damping material in the kit so I need somehting good. Blackhole5 is too expensive. Are there any cheaper alternatives that work well like batting material or fiberglass insulation? Also, how much do you usually need? All interior walls? only back and sides? BTW, I fired them up last night without the damping material to get started breaking them in. Right from the start these babies started singing. I am very impressed with these speakers so far. They are very detailed and precise with tight defined bass and I know they will only get better as they loosen up a bit. I will post more reviews of these speakers and the MB1's after the new year. Thanks!