Wow, you just made my memory do a back-flip.
My Dad had an audio power amp he was very proud of, which had four 807's in push-pull-parallel, a couple of massive transformers (power and output, of course), a pre-amp/phase-splitter (6SN7?). I recall the amp being associated with a mono "Voice of the Theatre" system. He had it hooked up and running for many years, but retired it in favor of a smaller stereo receiver sometime in the 1970's.
I worshiped that amp from the time I was a kid in the 50's until he passed away in 1996, but when my sis and I went through his things, the amp was nowhere to be found. I was heartbroken; I imagine he or someone tossed it believing it had no value in the modern age of solid-state amps.
*sigh*