Here is what I'm trying to describe. Possibly off base here, but here it is:
if two different transistor amplifiers have the same smooth, linear frequency response, low distortion, and are operated within their output ratings, then they will tend to sound identical until they are called upon to produce great quantities of clean, unclipped power. With one amplifier, there may be a quality of effortlessness to the sound quality on big dynamic peaks in sound level, whereas another amplifier may start to sound strained or harsh on dynamic peaks because it cannot handle peaks free of distortion. Using music as a “test” signal, such differences may only appear as a need to “turn down the volume” rather than your hearing gross audible distortion artifacts. Note, too, that peaks can be as much as 12 dB louder, which will demand 16 times as much power from the amplifier, causing many lower-powered amplifiers or receivers to go into clipping.
and:
One primary attribute is a ruler-flat smooth frequency response from the deepest audible bass signals at 20 Hz (or lower) to the highest frequencies we can hear, at 20,000 Hz. A smooth, linear frequency response means that the amplifier will treat every incoming audio signal, whether it’s a bass-drum signal at 30 Hz or a cymbal’s high-frequency harmonics at 10,000 Hz exactly the same way, increasing the electrical strength of each tiny signal by exactly the same amount. Low total harmonic distortion (THD), below 0.5%, is essential so that any distortion artifacts remain inaudible with music. Finally, generous power output from a robust power supply so that the amplifier can handle the huge range of soft-to-loud dynamics present in virtually every type of music and soundtrack. “Generous” could be defined as a minimum of 50 to 100 watts per channel or more. For realistic music reproduction, more power is always desirable.
