How much amplifier power do you really need?

[David A]

"How much power do you need?" is a complicated question and I think there's a tendency to think that there's a simple answer based on speaker choice/sensitivity and the peak volume your speakers are capable of but it isn't as simple as that and in reality you can find 2 people with the same speakers, one of whom might be really happy and perfectly satisfied with a 140 Pro and another who needs a 1000 Pro and who can't wait for Devialet to produce a 2000 Pro.

Not so complicated.  People tend to mistakenly think they need more power because they believe more power will sound better... because it's more power.  The sound quality of an amplifier has absolutely nothing to do with the amount of power it generates.  Sound quality is dependent on factors such as the choice of architecture (Class A, Class A/B, Class D, etc.), choice and quality of components (solid state, valves, hybrid, etc.) circuit topology and design (multi-layer boards, discrete vs surface mount technology, etc.).  Power is simply a means to an end.  To produce electrical energy that can be converted into electromechanical energy. The only way to know for sure how much power you need is by measuring what you need.  Most people will be surprised by how little they really need.

I'm sorry but it is a complicated question. You assume that "people" believe more power will sound better so they're asking how much power they need to make things sound the best that they can sound but if people simply believed that more power sounded better everyone would be buying D1000s and no one would be buying D140s. While you may argue that the depth of our wallets is a limiting factor that too isn't universally the case. Lots of people buy smaller amps than they could afford to buy. You've got a straw man argument going on.

The reason the question is going on is because of the factors involved, factors such as preferred listening and peak listening levels, speaker sensitivity, listening distance, room size and setup of the speakers and listening position in the room, room construction and furnishings, openings to other spaces and the characteristics of the other spaces. All of those things affect the level of sound we hear in the room for a given amount of power and none of them have anything to do with a belief that more power sounds better.

In an earlier post above you said  "…more power does not sound better than less power all else being equal."  I agree, all else being equal an amp with more power will not sound better than an amp with less power when both are producing the same SPL at the listening position but how often is all else equal? If you have a situation where an amp with more power sounds better than an amp with less power when both are producing the same SPL at the listening position then obviously all else is not equal. If you want to claim that an amp with more power can't sound better than a smaller amp which is also capable of producing the same level then you need to show that all else is equal and you haven't attempted to do that. I would respectfully suggest to you that when you compare amps with different power outputs, even amps from within the same range such as the 140/220/250 you will find differences apart from the power output so all else is not equal. That being the case I have to say that, at the very least, a difference in sound quality is possible.