But how do you know this foam you bought is equal in noise reduction to the Acoustipack pre-cut for Sonata?
I don't know this.
I've built quite a few speaker projects both as a hobbiest and projects while I was an engineering student. I've played with quite a few different damping materials. It is generally accepted, I think it's fair to say, that BlackHole 5 is the best internal damping material for these projects. I've purchased several sheets of this stuff at $50 USD per 24"x24" piece.
The BH5, like the Accoustipack, has three different densities to it's 1/2 inch thickness and it makes sense that it would have distinct damping advantages. I think I still have an unused sheet of the stuff. If so, I'll post a picture of what it looks like when I get home.
The thing is, testing at the SRC anechoic chamber at the U of S and also my own measurements with LSPLab and Nexus show no difference between BH5 and pourous, closed cell foam. Both of these materials provided comparable improvements over an undamped enclosure, however sleight. The improvements were audible and measurable (but just barely). A couple of the shinier carpet underlay materials provided no improvement at all.
I've come to the conclusion that many exotic and extremely expensive materials are wildly oversold and tend to appeal to the egos of golden eared audiophiles. You know... the guys who need to break speaker cables in properly to get the best sound.
As far as experience of, or knowledge with, the Acoustipak kit goes, I have none. I offer no data on that product. My observations are purely for the Princess Auto $6.99 CDN foam mat.
I have a calibrated panasonic microphone and the Nexus RTA soft/hardware, but I would not be able to produce any numbers that would be meaningful in this context. For that reason, I am simply providing a subjective assessment of this project. My assessment of this project is that while it provides an improvement, it is excruciatingly minimal and only worthwhile for silentPC zealots such as ourselves.