Back to report that
@rickb119 was right. I swapped the US-made Superones and finally got around to hooking them up for a late night listening session. Very smooth. The Chinese versions were forward and voiced higher. These are fantastic. In fact they sound quite similar to the Energy RC10s, but the Energys have more of the mids scooped, these are a bit more level. Respectable bass. Coherent is the word. Love em. I could live with these for all my near-field needs - I've recently gotten a clearer picture of where things are headed - or rather where they end. Getting rid of most of the amps and basically every speaker that isn't an ADS. This conviction was further cemented by the acquisition of L710s which needed new tweeters. Since Richard So is on vacation, I went and found some donor L400s, and couldn't pass on a deal for some L420s for 60 bucks. These three sets of speakers together yielded enough tweeters and woofers to run two pairs.
The L710s, ADS's smallest three ways, truly are fantastic. That same smooth ADS sound I found in the 1590s and 1290s. Why did I ever stray? But I gotta say, even though I agree a lot of the magic resides in the soft domes, the two ways are wonderful in their own way. I recently picked up a Sansui AU-222, what I consider my final amplifier acquisition, and have it set up in the garage as I work on it, along with the L420s. Man, what synergy! I don't think I've noted such musicality before. Waiting on a mouser order to finish the restoration of the 222, and then the speakers and amp both come inside.
I even re-painted the 222 the same color as the grills on the 420s..
View attachment 3508193
All of which is to say, I think I could be happy with any of these speakers -
Ascend Sierras
Vienna Haydns
Energy RC10s
NHT Superones
ADS L420s
The less impressive for me were the ADS L300e I also picked up from the same guy who originally sold me my L1290s and the L400s, and the Cantons. The L300es will probably become my tester speakers just because they're small and space is at a premium in the workshop. The one leftover pair of Cantons will be sold, as will all of the other speakers except the ADS and NHTs. As impressive as new speaker technology is, especially in the realm of bass reproduction out of tiny enclosures, I just don't need more than one pair of 'smooth small bookshelves'. With that, I conclude this thread. Thanks to everyone for their recommendations.