In practice 30mW sound much louder than we expect

The ear and mind perceive inverse exponentially of logarithmically.


And the non linearity of class A amps at peaks make the perception of sound loud by our brain


References:


Sound and Hearing - Stevens, Warshofsky - Time-Life science series


http://euroelectron.blogspot.gr/2018/03/madonnas-voice-coming-from-point-source.html


Tubes vs Transistors (vs op amps), Is there an audible difference? - Russel O. Hamm - JAES