Greetings, Denizens!

[RoyY51]

I have this little project going on and I am looking for some suggestions. I'm trying to find the most beneficial sound absorption/sound altering material that is available. This material will have to fit into 5"x5"x7" spaces. There will be 2, 3, or 4 spaces (depending on desired height), incorporated into stands under monitor-sized speakers. The spaces will be open front and back or side to side. I realize that 5"x5"x7" is not a big area to fill with something that will make a noticeable difference in sound quality, which is why I'm looking for the most effective material possible. Please don't bring up Shakti Stones or tuning forks...I'd like to keep this real.

Thanks in advance for your help!