Window treatment ---Recommendations on fabric?

I have a lot of window area in my listening room and acheived very good results by treating my windows with Marigo VTS dots. I gained more focused and palpable images.

Hunter vertical blinds makes a Honey comb. It works quite well for some absoption and diffusion. For absorption heavy natural fiber of two different types, have a liner of heavey loose woven material like denium or wool and a lighter fabric on the outside. You need a gather of about 50% when the drapes are closed. This will work quite well. Short of replacing the inserts in the glass there is little you can do about the bass leakage.

Thanks to you all for the advice.