Not meaning to confuse the issue here, but I noticed reference in the responses to 3dB being a level difference where doubling the power is necessary. This is true of course, but I wanted to point out that it takes about 6 to 7 dB of boost to double the PERCEIVED LOUDNESS (for the midrange of the music spectrum). This translates roughly into QUARDUPLING the amps power output to double the perceived loudness for a given speaker. Many feel it's the FIRST watt of output that counts most toward listening satisfaction, and those in the Triode camp take pleasure in that. Hope this is useful.
how much tube power is needed?
Let's say, for a 86 and a 92 dB efficiency speaker. SE triode fans say 10 W is enough, 20 W is more than you need. They use horns and high-efficiency speakers (> 92 dB sensibility). They say high-powered designs do not sound good at low volumes while driving high-efficiency speakers. Others (mainly push-pull fans) say that even though you have high-sensitivity speakers, the more watts, the better dynamic resolution. I don't want to launch a SE/PP war now. This is not meant to be a pure technical question, it also concerns musical taste. What is your experience with these?