Transparency: What speakers have it in spades?

The way I am thinking about transparency these days is operational and not musical: the more a component allows me to hear upstream system changes, the more transparent it is. I'm sure this definiiton is not without problems and I'll also say that transparency thus defined is not necessarily a good thing (except for a reviewer perhaps). But I think it's a good, valid definition.

By this definition, the most rransparent speakers I ever owned were Quad 57's. Thiels and Avalons were also very transparent. ProAc and Harbeth: no, sorry. Of course, I was younger when I had the Quads and I think could hear differences more easily.

Transparency means to me the ability of a speaker to, through slight of hand,
step out of the picture. To do this, it must minimize coloration, must be
crossover and driver seamless, and preferably be full range. Size doesn't
matter. A successfully transparent speaker can be a big as my Scintillas, as
long as they don't flinch while creating a Mahler crescendo, they just don't
come to mind.

Drubin:

Using your operational definition concur--the Harbeth's should not be on the list. Any speaker that sounds that good no matter what you put in front of it is not "transparent" by your definition.

Exactly.

All of these are very transparent, but I haven't personally auditioned any of them:
Transparent speaker(s) #1
Transparent speaker #2
Transparent speaker #3
Transparent speaker #4