DCM Time Window 7 - AMP & PREAMP

Just to clarify something- a 3dBa increase in SPL (Sound Pressure Level) is double the loudness. dBa is a log scale so amplifier power must double in order to double the loudness of the speaker. It takes a just about a doubling of the loudness for our ears to perceive a change. It is important that speakers maintain a linear relationship of loudness output to power input. Overall average SPLs may not get that high when listening to music, but the peaks can require a lot of power and that is the advantage of having a high powered amp. It can generate those peaks to make the sound more realistic.
Take for example, a speaker with an efficiency rating of 89dB. That means it generates an 89dB SPL 1 meter away at 1kHz with 1 Watt input. Double the SPL, 92dB requires 2 Watts. Double again is 95dB and requires 4 Watts. 98dB, 8 Watts. 101dB, 16 Watts. You can see that since even loud listening levels are around 85dB average amplifier power needed is very low. The power is needed for the musical peaks. A bang on a bass drum, even a sharp clap can peak at over 105dB. The closer an amplifier can come to duplicating those real life high power peaks, the more realistic the sound is to us. But the other problem is that speakers start to become non-linear at some point around or above 110dB. Some speakers hit their maximum output there. It is hard to say, not many manufacturers publish maximum output or loudness vs. power curves.

Ok, 3dB is double the Sound Intensity. It is still correct that it takes about a 3dB change in Intensity then, to perceive a change in sound level. 6-10dB which is double the loudness is a very big change. Think about normal conversation- it is 40-60 dB. Long term exposure to 85dB SPL will cause hearing damage. 100dB is standing next to a jack hammer. If someone must shout in order to be heard over your music, then it is very loud and likely approaching 75-80dB at the position where they are standing. Also consider that the sound Intensity then, drops 3dB every time the distance away from the speakers is doubled. So if sensitivity, for example, measures 92dB at one meter, then it drops to 89dB at 2 meters. And lastly, if each speaker is generating 92dB, I think the combined SPL is 95dB.