Dec 04, 2012· Power is expressed in watts. But in the case of audio amplifiers or AV receivers, there is a lot more than just watts; a typical amplifier power rating is defined as say '80W/Ch RMS 20Hz20kHz, 8 Ohms % THD.' This means that the amplifier is capable of delivering 80 watts average power per channel into an 8 Ohm speaker load at a maximum % total harmonic distortion over the specified ...