Help with Audio 101. What's most important to sound quality?

[Gerall]

After performing many of the subtile tweaks like Dynamat, interconnects, and speaker cable upgrades....., I found that proper speaker placement and alignment made the most difference. Took 3 people with me in the sweet spot, and a bunch of measuring and calculating, but wow when I had the speakers placed and aligned for optimum, the sound difference was considerable.

[westcott]

Components come and go but quality speakers will last generations and have the biggest impact per dollar for sound quality. Room acoustics are a close second and proper speaker placement, seating distance, room orientation are all key to taking full advantage of a good speaker and sound system. Room acoustics and speaker placement is not expensive if you select the right space to begin with and do some homework on what constitutes a proper approach and provides the best bang for the buck.

[Wireworm5]

Another chance to go head to head with Kex.
I don't doubt that speakers have a great variance in sound characteristics. I'm not saying speakers aren't important, heck all of the components are important to acheiving good sound. But I still maintain that the amps/receiver are the foundation to great sound and this is where the most emphasis should be placed.
I'll use my Bryston's as an example as this is what I'm familiar with. Now I use both B&W DM 601's and Paradigm Studio 20's v3. On my Bryston 3B-ST both speakers sound good with slightly different sound characteristics. Now change the amp to the 3B-SST and both of these speakers now have an airy quality. Neither of these speakers exhibited this trait with the ST or even my Yamaha av/receiver. So I conclude (not having experience with real expensive speakers) that what I consider elite sound is not possible without the SST amp and the speakers exhibit that quality, the source, as well as their characteristic traits.
The reason nobody has heard differences in amps in DBT is because it's attributed to speakers. I assure you that the amps/receivers makes the biggest overall difference in what a speaker is capable of.

[kexodusc]

Another chance to go head to head with Kex.

??? Don't recall ever going "head to head" with you.

I'll use my Bryston's as an example as this is what I'm familiar with. Now I use both B&W DM 601's and Paradigm Studio 20's v3. On my Bryston 3B-ST both speakers sound good with slightly different sound characteristics. Now change the amp to the 3B-SST and both of these speakers now have an airy quality. Neither of these speakers exhibited this trait with the ST or even my Yamaha av/receiver. So I conclude (not having experience with real expensive speakers) that what I consider elite sound is not possible without the SST amp and the speakers exhibit that quality, the source, as well as their characteristic traits.

Actually, I have the same opinion as you up to this point, more or less.

The reason nobody has heard differences in amps in DBT is because it's attributed to speakers

Not sure what you mean here? Nothing is attributed to the speakers. They remain constant. The only thing that changes is the amp. Yet despite changing the amp, nobody can reasonably prove under blind conditions that the sound changes.
When we keep the amp constant, but change speakers, more people notice a difference in sound. Hence, speakers have more impact than amps on sound.

I assure you that the amps/receivers makes the biggest overall difference in what a speaker is capable of.

I agree with this statement as well. But the question isn't what makes the biggest difference in what a speaker is capable of, it's "what makes the biggest difference in overall system sound".
Put differently when building a system, which component will generate the greatest benefit per dollar spent? What would sound better? $300 speakers and $2000 amp, or $2000 speakers and a $300 amp? In my system, a better speaker always sounds better than a worse speaker regardless of the amp used. Better amps, just help the better speakers sound better still.
Now, with diminishing returns and all, there comes a point where an amplifier upgrade is more cost effective at producing X% improvement than a speaker upgrade.