Hi Joe, I understand your empirical position as being real, but I would not regard it as universal by any means with regards to OTLs and rear-loaded horns. It simply means that the amp you used sounded the way it did with that speaker, and it does not follow that that is true of all OTLs on the same speaker.
IOW it may be that your experience was real, but that it may well have been possible to make that OTL work better by playing with other variables- speaker cables and power cords come to mind- OTLs usually don't like long speaker cables and can be quite sensitive to cable design! BTW most OTLs other than ours use a lot of loop feedback, which can cause them to sound thin on a speaker that is built with low or zero feedback speakers in mind. see http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php for more information.
IOW it may be that your experience was real, but that it may well have been possible to make that OTL work better by playing with other variables- speaker cables and power cords come to mind- OTLs usually don't like long speaker cables and can be quite sensitive to cable design! BTW most OTLs other than ours use a lot of loop feedback, which can cause them to sound thin on a speaker that is built with low or zero feedback speakers in mind. see http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php for more information.