I'm curious if you checked low frequency limits with the Plitrons. While their toroidal transformers tend to perform better at high frequencies than typical EI designs, when I tried to run them full-range-ish, they saturated/distorted more with bass at high levels (compared to a Tranex 2-0404 or a trio of Hammond 1609's).I didn't like the factory SUT's and replaced with Plitron
heating PTFE above about 475 F can generate toxic gasses, including HF.
I also think there is much much more to it.It turns out our $9000 speakers were held together by good ole bookbinding glue, aka polyvinyl alcohol, in other words hot stick glue from the crafts store. When I took off the dust cover there was a strong smell of "old library". Surely the extra $0.02 on the BOM for a few dabs of quality epoxy would have killed them profits.