What speaker could safely be ordered without hearing it first?

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. 

I would suggest some of the youtube reviews by some of reviews with high traffic. Old timer story......In 1970 or so the only place you could buy stereo equipment at a discount was out of NY with ads in the back of Stereo Review. Being from a small town in Minnesota, mail order was your only option. I bought a pair of Altec Lancing Santana speakers, monsters with 15" woofers, walnut cabinets and slate tops, large end tables really. You had to tear out an order form, fill in your stuff, add up the cost, write a check and send it off to NY and then wait. I had them shipped by freight (only option) and my mother took me down to the local train depot and we picked them up in dad's truck. I think I paid under $400 for the pair with shipping. Ahhh, nostalgia!