A fair assessment - can't say I disagree with many of your points. It's obvious that Dan Clark Audio has subscribed fully to the "Higher Price = Higher Mind Share" doctrine. There's nothing wrong with that, though. In today's market, a lesser-priced flagship often struggles to capture the attention of the market, no matter how good it sounds. Case in point - I am sure that the AH-D9200 would be better received if it had a higher sticker cost; say, $2,500 or more? Somehow, I think that it has been relegated to the back benches precisely because it isn't priced like a bona fide flagship.It’s a fair point that pricing IS part of marketing and PR (I can vouch for that professionally), though any good marketing team will also carefully weigh how much of a turn-off the price might be. However, when you are operating in this niche space, you have more flexibility, as 1) you don’t need to sell a large number of units annually and 2) price sensitivity is much lower due to limited competition and the buyers’ ability to spend thousands of dollars for a luxury item.
To your question of doubling of SQ with a doubling of price- the answer is “no”. Hence the point of diminishing returns. I have not heard the Ether C Flow 1.1, but it’s very safe to say that improvements are incremental rather than multiples (Yes, I’m extrapolating from the Focal lineup).
That doesn’t mean the Stealth isn’t worth it if you have $ 4,000 to spend on headphones, of course- merely that you will get the vast majority of the performance at a lower cost.
Then again, our hobby is about achieving the last percentiles of performance to help create the illusion of a live performance (or at least, that’s how I see it). And so we yearn for the ultimate musical experience…
Sadly, the same can be said for many of the other reasonably-priced flagships available today. Hell, even the Vérité Closed appears to be a (great) bargain in the world of top-end (closed) flagships; the Rögnir, the Stellia, the HE-R10P, and now the Stealth are all priced higher.
Still, this hobby, and the industry, as a whole, will continue to advance; hopefully, the innovations and improvements will continue to match the growing delta in price.