Specs from the manufacture are one thing but I've learned that they only can mean so much depending on your room and placement. I'm trying to figure out true frequency responce ratings for a Sony SAWM-40 (20hz lists) in my 14x17 room that's opne to another smaller room. Just what is doubling? How do I know if the Sony is doing this to get the ratings it's listed as?? ALso, what's a good test tone CD with music material also that I could buy easily without hunting all across the web for one?? thanks everyone.