matty said:Too much foam will remove the 'feel' of the room and you end up with a dead environment with no echo, some people like this, but a balanced room with the right balance of absorption and diffusion is better(for me personally and professionally, lol)
Very important point that. From my experience, once people head down the acoustic treatment route, they tend to put too much absorption in the room. Your will definately hear a difference doing that but don't loose sight of the fact that a highly diffuse sound field (within limits) is really better for music than an overly "dead" acoustic environment.
Home cinema is an exception where a low reverberation time is preferred as the soundtrack is mixed with that type of playback environment in mind (i.e. cinema).