I don't know about that. I have heard many high efficient speakers which I do not consider higher sound quality. Back in the day the best sounding speakers to me were almost always at the opposite end of the spectrum. Low efficiency speakers were usually more accurate sound quality. The typical high efficiency speaker, many times horn loaded were not my cup of tea, so to speak.
Therefore finding a higher efficiency speaker with super accuracy (European sound) would be the Holy Grail for me
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