It is almost always peak power, summed across every channel, and often measured at a distortion level nobody would listen through. It is not a measurement you can compare to another brand’s.
The three figures that share the word “watt”
RMS with conditions — continuous power into a stated load, over a stated bandwidth, at a stated distortion. This is a measurement. Peak — the largest instantaneous value, for a fraction of a second. PMPO — a marketing figure with no defined method at all.
How the big number is built
Take the peak figure per channel, multiply by the number of channels including the subwoofer, and print the total. A “1 000 W” 5.1 system is often five modest amplifiers and a subwoofer, summed at peak.
What to look for instead
A power figure with its conditions attached: “100 W into 8 ohms, 20 Hz–20 kHz, two channels driven, 0.08 % THD”. Manufacturers who publish that are prepared to be compared, and they are the only ones who can be.
What actually changes how loud a system plays
Speaker sensitivity, in dB at 1 W and 1 m, and the size of the room. Both are published, and both matter more than the wattage printed on the box.
Questions people actually ask
What is an RMS figure?
Continuous power the amplifier can deliver, stated with the conditions it was measured under: the load in ohms, the frequency range, the distortion level, and how many channels were driven at once. All four matter, and a figure without them is not comparable to one with them.
Does more power mean louder?
Less than people expect. Doubling amplifier power raises the level by 3 dB, which is a small perceived change; speaker sensitivity moves the same amount for far less money. A sensitive speaker on a modest amplifier plays louder than an insensitive one on a big amplifier.
Last reviewed 4 September 2026