What speaker could safely be ordered without hearing it first?

Quad 57 from Electrostatic Solutions. 

Think they are now $6K.

I have owned Tannoy Westminster Royals, ATC Anniversary 50, etc.

Once you hear the tone and transparency of 57s there is no going back.

Human Speakers model 81 DK ... aprox $1250 / pair

Tannoy Legacy or GR speakers, end of game...

Speakers are the most subjective link in the music chain of all, even tge moreso by being placed in a different room than whatever "typical" room they were designed for, and whatever electronics they may have been voiced for. To that end, after many years of making and building customs for others, I finally built my endgame speakers. 

People seem to like them, but I have no doubt they don't conform to anyone's idea of what great measured performance is, and that's on purpose. I listen subjectively.  So any speaker may be safe for you to buy unheard, but it's also a safe bet IMO it won't be exactly what you wanted in your own system in your own room.

If you find Castle speakers on the used market for a few hundred bucks, then get that. That may as well be my final answer. You'll get real veneer and decent drivers/parts.

Some sellers are so desperate that they even give away the optional wooden stands for free. Unlike with JBL or Klipsch, you won't get any recognition from the audiophile community.

But you won't overpay for something that's "just fine". Castle is like the most uninspiring brand with the least curb appeal.

Castle is just like Harbeth without the name recognition and the same bland design. That's great for your wallet. It's kind of like a buying an Infinity on the used car market. The depreciation is insane because nobody cares. I see beat-up Honda Civics sell for more.