"I'm a believer"

I've been to three audio shows in the past several years (Axpona, Tampa, PAF) and I have come to the conclusion that the concept of diminishing returns doesn't apply very well to speakers. Rather, there is just no solid correlation between price and performance. Like the OP I have heard megabuck speakers that didn't sound good and I've heard several moderately priced speakers that sounded wonderful. I don't think that I can attribute this to non-optimum amplification or source equipment because I trust the speaker manufacturer to know what components work best with their speakers. In many demonstrations the cables and power conditioning cost more than my entire system and I my system was better, at least to me.

To put it another way, I've heard six-figure speakers that sounded amazing and I've heard others that sounded mediocre. I'm a geezer - I've had this hobby for 50 years - and I've concluded that once you get into the audiophile range of gear (thousands of dollars per piece, not hundreds) the value proposition seems to break down. One would think that a million dollar system would be life changing but I have not found that to be the case. It's not that diminishing returns takes over, it's more that it's a crapshoot. My favorite speakers of all time are the MBL 101 E Mk II and while they are certainly expensive ($80K) they outperformed speakers that were multiples of their price.

We have to take into account that a manufacturer’s "statement piece" is just that. It is a statement of the capabilities of the manufacturer. This would suggest a "no compromise" approach to EVERY aspect of the speaker in the range of "world class" speakers.. This would mean that everything you see, touch, and HEAR would stand up to (or exceed) the best of the best. Including esthetics.

I would suggest that the "law of diminishing returns" starts at about $50. Part’s Express offers a pair of 4 1/2" 2-way bookshelf speakers for around that price. Okay, you double the price ($100) and get bass extension. So, are improvements to 2 of the 10 octaves worth TWICE the price. "Common sense" say’s "No!!" The emotional, audiophile side of us says "Yes!. So, we keep doubling the price until we arrive at, say, $60k. Is a $120k speaker twice as good? Just revert back to the $50-$100 upgrade example for your answer. The same rules apply.

So the "ultra top end" has a market for those whose life choices are "this AND that", unlike us morals who have to choose between "this OR this."

Hope those six figure speakers hang around for a while. Even if their "diminishing returns factor" don’t pass the "4th grade math" test, yet put a smile on the faces of their owners.

There is definitely a Rule of Diminishing return just as there is the Sunk Cost Fallacy. I suspect that the Venn diagram of those two circles would be close to one circle in some cases for certain audiophiles. For example, someone subconsciously suffering from the Sunk Cost Fallacy has spent years and enormous amounts of money in their pursuit of perfection and yet never attain it as perfection does not exist. So each subsequent purchase is rationalized as moving closer to audio perfection. Yet the reality is they would not / could not admit - even with hard facts -  that the recently purchased $100K speakers are marginally better or equal to the $10K speakers or even the $5K speakers because they suffer from the Sunk Cost Fallacy. The diminishing returns set in long ago for each dollar spent.

The Rule of Diminishing Return applies to many industries where the marginal performance gains do not justify the cost, yet at the high-end market of consumable goods, the real reason is justification for many that they can exhibit how they can "afford" to pay $150K for certain speakers, or $200K for a vintage Jaguar, or any luxury item for that matter. Some may actually know they're getting no real qualitative improvement for their investment because the point is to exhibit their wealth. 

i concur with your post description...

I will only add that sound perfection does not exist and as you said it is true ...

But the acoustic factors scientifically really exist that described all aspects of good sound in acoustics ...

Because most people focus on gear price tag for audiophile experience not on acoustics factors which are way more deep than only room acoustic , they accept to spend money but they dont invest the big amount of time in the acoustics necessary studies and experiments ...

They became then obsessed fetichist and brag about their fetisch chosen  object sold by them as a solution to all problem ( for exemple EQ or cables or tube amplifier etc )  ... The gear and cables are their hobby ... My hobby was for few years acoustics thinking and experiments to create a good audiophile experience at any price with anything reasonnably good and with synergy for sure to begin with  ... Acoustics principles and facts dont change with price or specs  of the gear ...

And for those who dont know how to read, i dont claim that my speakers at low price beat more costly one in performance ... I claim that there exist a minimum acoustical satisfaction threshold and we can pass over it at low price if we understand basic acoustics ...

There is definitely a Rule of Diminishing return just as there is the Sunk Cost Fallacy. I suspect that the Venn diagram of those two circles would be close to one circle in some cases for certain audiophiles. For example, someone subconsciously suffering from the Sunk Cost Fallacy has spent years and enormous amounts of money in their pursuit of perfection and yet never attain it as perfection does not exist. So each subsequent purchase is rationalized as moving closer to audio perfection. Yet the reality is they would not / could not admit - even with hard facts - that the recently purchased $100K speakers are marginally better or equal to the $10K speakers or even the $5K speakers because they suffer from the Sunk Cost Fallacy. The diminishing returns set in long ago for each dollar spent.

The Rule of Diminishing Return applies to many industries where the marginal performance gains do not justify the cost, yet at the high-end market of consumable goods, the real reason is justification for many that they can exhibit how they can "afford" to pay $150K for certain speakers, or $200K for a vintage Jaguar, or any luxury item for that matter. Some may actually know they’re getting no real qualitative improvement for their investment because the point is to exhibit their wealth.

One thing for certain is how much speaker is needed to get the job done well relates mainly to room size and the cost to get the job done well in most people’s rooms at home is moderate on the grand scale of how much speakers can cost. Overall design and build quality does matter and powered subs are a great way to get the job done easier and for less cost. BEyond this the other things that matter are getting the right speakers for the room set up well and personal preferences.

On the overall cost scale, a pair of Vanatoo acitves alone can get most folks over teh finish line alone at least in a smaller room for well under $1000. Add a sub and you have a setup that is hard to fault in most rooms. These in particular are overachievers in a small package due to smart design including nicely applied DSP and built in amplification (each is bi-amped....no kidding!). Check them out! I would suggest any newcomers start with these and if you determine you need better from there go for it!