As someone who likes to listen to music, I also like to understand what makes it so that I go “wow”. So I often read forums like ASR, Reddit, and other forums in order to learn more. And I often encounter a question that I think I can help with, because I was wondering about that too.

The question is: “how much power is enough?”

There are various answers to this. The main one is that you should have enough power to listen at a volume that doesn’t give you permanent damage to your hearing, while still maintaining enough reserves for the whole dynamic range of the music. Yes, the more the merrier, but your 1000W amplifier will never even use a fraction of it.

The basic reasons for that is that most loudspeakers can produce 87 dB of sound pressure level (SPL), which is at the point where you can get hearing damage if you listen to it for a long time, with just 1 watt of power. With some caveats, of course: distance reduces the level, and so does bass. If you are a basshead you will need more power for your 20 Hz bass notes. Actually, you’ll need 50 times more. So 50W per channel should do the trick on even the lowest bass you can still hear.

Normally, however, people will get a subwoofer and save the amplifier’s power for the higher frequencies. This is, incidentally, why 20W tube amplifiers are common for stereo hifi listening: if you don’t put out a lot of bass and listen at 55 dB, you can get by with 20W no problem.

In order to play with various options, I wrote a little calculator in javascript (and also because I just wanted an excuse to play with VS Code, docker, some extensions, and do a little CSS styling with flexbox).

See for yourself how this all works out in the SPL calculator at https://www.grundsatzlich-it.nl/spl-calculator/spl-calculator.html.