Is the denim better, or is foam just as good? It's the R6.7 denim that seems to be sold out everywhere. I can find R13, but I don't know if that's a problem (for HT-8s.) It says R6.7 is 1.6" thick and R13 is 3.5" thick. So, which is the best option: 1) Wait until R6.7 denim comes back in stock. (No idea when, though.) 2) Go with R13 denim now. 3) Go with 1.5" thick acoustic foam now.