I don't think you understood my thread. The recordings were made out of doors (except for the pipe organ of course) so that no reverberation would get on the recording. That way the signal is as pure instrument and free of acoustics as possible. Upon playback, the speaker playing the tape alternates with the live musician. The acoustics of the location of the demo treat each the same. That way, you get the best comparison of how well the speaker can accurately reproduce the live instruments or more succintly, its accuracy. Were other speakers present? No why should there be. The demo was for the purpose of showing that AR speakers were accurate on an absolute basis against live musical instruments, not that they were superior in the same demo to someone elses model? If someone else has the guts to do the same with their equipment, they would do no differently.

" can we say it sounds accurate in absolute terms."

Yes that was the purpose of the demonstrations.

"the most efficient speakers or speaker systems i've heard are great with dynamics and headroom.i've heard altec 604s and 605s in open baffles, several versions of ALTEC voice of the theater, SET tri-amped JADIS (a french brand) eurithmie of , Klipsch, Tannoy Westminster"

RGA says Klipschorn is one of the ten best speakers in the world. If that is his opinon, there no point in further discussion. I've heard folder horn and folded corner horns like Klipschorn and A-7 many times. IMO, they are awful. So colored as not to be taken seriously as high fidelity sound reproducers.