I found some low sensitivity speakers(80 to 86dB)sounds much better at higher volume. It seems to be a threshold volume for this type of speakers to sound right. At low volume, the tonal balance is usually no good. Examples are ATC passive monitors and my pioneer S-A4SPT-PM. Higher sensitivity speakers such as proac, elac and many full-range one sound right even at low volume. Is this their inborn characteristic?