Q. My speakers are 300 watts “MAX” and 90 watts “RMS” what size amplifier do I need to drive them to achieve the best performance?
A. Whenever you are choosing an amplifier to drive speakers you should use the “RMS” ratings rather than the “MAX”. Always define which ratings you are comparing (RMS or MAX) and try and match the RMS rating of your amplifier to the RMS rating of your speakers.
“MAX” Power Rating
The “MAX” power rating (also known as “PEAK” power) of a speaker is the amount of power that the speaker can handle in short bursts or peaks, without causing permanent damage to the voice coil. If this rating is exceeded constantly you will risk burning the voice coil.
“RMS” Power Rating
The “RMS” rating of the speaker is generally considered to be the nominal constant power that the speaker will handle continuously without causing damage.
Therefore if your speakers are rated at 90 watts RMS, you should drive them with an amplifier that is capable of supplying 90 watts RMS per speaker or as close to that as possible. That is not to say that an amplifier capable of a higher output cannot be used if the amplifier settings are
managed responsibly, realising the potential to overdrive your speakers exists.
This rule also applies to using an amplifier that is under driving your speakers. Constantly driving a distorted signal from an over driven source to your speakers can cause damage to the speaker voice coils.