How much does power amplifier really matter comparing to other hi-fi components?

“How much does power amplifier really matter comparing to other hi-fi components?”


Lots and lots.

Lots of variables to consider, particularly speaker sensitivity and listening levels. 

Generally speaking, you never want to get even close to maximum power, even with short peaks because manufactures usually specify amplifier power when it reaches 1% THD. THD often rises quickly once you get close to maximum power, so keeping 10% below rated power is generally fine and is often close to minimum THD+N.

Provided you are willing to always keep the volume control well below maximum, consider a higher rating than speakers as they are can accept term short peaks without damage.

A good starting point, but always check specifications.

the secret is that speakers are the most important element ... BUT YOU SHOULD SPEND MOST MONEY ON THE SOURCE ...

50% speakers
25% Amp/preamp
25% sources (me: 2 TT's stereo, mono, tuner)

This is a massively complex question. It sounds like you want to build a high end system from scratch which can be a big job, particularly with the reduced number of dealers. I'd find an audio dealer whose taste runs to your own and begin the work. What kind of music do you prefer, what's your budget, size of the listening room, do you have any pieces already to carry you for a while.... are all things the dealer can use to guide you.

To  your specific question, in terms of amp vs. pre-amp I'd put more into the amp. As others above have noted, the amp is tremendously important. Say 2/3rds to amp and 1/3rd to pre. Similarly, I'd spend more on the DAC than the transport/streamer.
I agree also with pani that the speakers and amp should be purchased and matched together. 
Good luck!!