Thanks Earl, I was going to scan my owners manual too but I’m out in Tokyo for the weekend. I have the same question on the 50ohms nominal and I’m asking Roger. The backplate uses the same bass transformer, (just in case some people don’t know, there are 2 transformers used in the full range panels – one for bass and the torroid which is used for mid~ high frequencies) I have a great ‘Roger explanation’ for why there are 2 transformers , just not sure if there is interest?
I’ll get back to you on the impedance rating.