I'm sure this is a total rookie question but I'll ask it anyway since I'm sure I'm not alone in wondering this. With the return being so small compared to the power input what benefit is there to spend $1000 (or any amount) on an amp?
In most cases, there is no real benefit, only the placebo effect. But, as Midcow2 says, there are speakers that are low impedance, or inefficient, and they may benefit from better amplification than what one typically finds in the average receiver. That is why, the first thing you should pick are the speakers you want, and then select amplification according to what you need.
In most cases, people budget their money very improperly for optimal sound. I was running a surround system with a receiver that retails for about $600 with speakers that retailed for well over $6,000. It sounded great (as it should with such expensive speakers). Because I wanted more features, I replaced the old receiver with one that retails for about $1600, which happens to be able to put out about twice the power of my old receiver. Guess what? They sound the same, unless I engage a feature that I did not previously have. I did not need any more power than what I originally had, as my speakers are an easy impedance to drive, and are of normal efficiency, and I have a normal room.
In most cases, people who add a power amplifier never level match it and compare it to their receiver's amplification in a blind listening test, so they never properly test whether or not it really helped. And with human beings, once they have decided that something will help and they spend the money and go the trouble of adding it, most likely they will be convinced that it really did help, even if there is no real benefit. Since most people have no concept of proper testing, it is easy for them to believe all sorts of things that are false.
Although your question is a rookie question, it is a very good question to ask.
