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

I wasn't too worried about the amp as long as it was quality built and powerful...but the Benchmark AHB2 changed the game for me. It made a very noticeable difference in my music.

The SOURCE (LP or Digital) is the most important thing and its integrity is responsible for more than 50% of the sound quality.

Oh, except for the quality of the AMPLIFICATION (preamp+amp) which is responsible more than 50% of the sound quality.

Oh, except that the SPEAKERS have the greatest variability, and are responsible for more than 50% of the sound quality.

Oh, and don't forget the ROOM. It will color everything, and is responsible for more than 50% of the sound you hear.  

There you go...... It's all very logical.

In my opinion this is a shifting % which is dependent on a few items. Budget, difficult speakers to drive and speakers that are extremely detailed. These items in my opinion will loosely dictate where the percentages of money should go assuming you plan on using a source, preamplifier and an amplifier. Source in vinyl is the platter, arm, cartridge, phonostage and cleaning machine. In digitial it is a transport, DAC and streamer.

A very modest budget will require more money to be placed into the speakers budget then followed by source. The pre and amplifier can be split.

A moderate budget will require the most money to be placed between the speakers and source, then followed by the preamplifier. As long as the speakers are friendly to amplifiers the amplifier will be last in line.

A budget where money is of little concern or you have spent the better part of a lifetime upgrading and now you are in that expensive category of equipment when upgrading then go fairly even in all the categories. The goal is to balance everything out because it will be really easy to hear the weak link when you have top tier equipment to chose from. Skimping anywhere will be heard. In this category the speakers will be slightly ahead of everything but source, amplifier and preamplifier all should be split as evenly as possible.

Difficult to drive speakers require quality amplification so go heavy there.
Lastly if the speakers you chose are extremely detailed then go heavy on the preamplifier and source.
Of course this is my opinion and how I went about thinking through my upgrade path and it worked well for me.

Wow

IMO, From most to least important:

1. Budget
2. Room
3. Speakers
4. Amplification 
5. Sources
6. Cables
7. Rack