What speaker could safely be ordered without hearing it first?

Rockport of course. Check out the reviews and comments on the forums. Universally praised as some of the best speakers made. Good luck !

Vandersteen

I think this is an important thread, because the reality is that for many of us, it is very difficult to audition speakers in your home with your equipment, the only way to really be "safe."  While that is certainly the best approach to a major purchase, if you deem that it is not feasible, you have received a lot of good advice for alternatives. Listening at a show, or probably better, at a dealers store would probably be worth a bit of a trip.
You are probably safer, meaning, the result will be more predictable, if you buy high quality speakers from an established manufacturer, such as Sonus Faber, Focal, Magico, Wilson, and many others. These brands are more likely to have a predictable house sound. Obviously, something a little more esoteric will be less predictable.

This topic is one more reason to lament the shrinking number of high end, brick and mortar Audio stores. 

This is like ordering a mail order bride! Don't do it!