Wow Naige, I've been so busy myself, that I hadn't seen this thread at all! Very cool project, & a lot of work. I'm sure many here will be either wishing they were doing a similar project, or doing something along the same lines. Either way, this thread is wonderful, & a gold mine of information. I've been thinking of converting part of my garage space into a rehearsal/occasional low end recording space for some time, so I'll be watching your progress with extreme interest. I'm especially interested in the "room within a room" construction, as my garage space is just single clad timber walls at present, so such a construction would be critical to success.
Good luck with this mate!