Performance stability of the amplifier: The performance stability of an amplifier influences the sound.
follow e.g. B. several strong impulses (like strong drumbeats) one after the other, a amplifier have as large reserves as possible so that you don't have to "take a breath". There are several important indications for performance stability.
The amp gets the power/Performance usually "not directly via the socket", but via its components: electrolytic capacitors, Power Supplies, etc.
( Exception: "Class A")
The size/performance of these components can often be seen through the ventilation slots from above into the interior of the housing. The cooling fins in the device ensure the necessary cooling of an amplifier. The greater the mass/or Outer surface of the cooling fins, the better the heat dissipation and thus the Klang.