Garage Listing room

Thanks for the replys. The garage listening room will still have all the shelfs, table saw ect still in there.

Its definatley a dead sounding enviorment, The wall are solid stucco on the outside.

Maybe framing a good solid wall infront of the Main door.

Going to bring in a set of speakers and amps and listen to someting fimilair, the room the system is in now are almost the same dimensions, will report

Thanks for replies

From what I just read on the web, the STC rating is a limited frequency power rating apparently measured in dBs. Acoustic power says 10dBs is approximately what we perceive as twice as loud (or half as loud). So a rating of 43 vs 33 would be twice as quiet (approximately). But don't forget that is a limited frequency measurement, not the full audio spectrum. 

QuietRock 545 is better then drywall. (STC-rated Assemblies ASTM E90:

60-80)

https://www.quietrock.com/products

@hiend2 "Going to bring in a set of speakers and amps and listen to someting fimilair, the room the system is in now are almost the same dimensions, will report" there you go. Listen and see what you have.

Since you will still be using the space as your garage and/or shop you may consider putting some drywall at selected locations on the walls to help reduce the amount of absorption in the space. Less about isolation and more about room acoustics and reducing the amount of absorption. I would normally suggests just using plywood on the walls in a space like that so you could use it to hang shop/garage items but sheetgood products like plywood and particleboard are still very high cost relative to last year. Drywall is more expensive as well but nothing like plywood. If you have a shop I'm guessing your relatively handy and you can hang the drywall yourself. Don't need to finish it if looks aren't a concern but this will help reduce absorption in the space. Best of luck!