[morzh]

Arran
but at least this model used a proper rectifier tube.


....which I had to change - the only bad tube in the whole radio. The rest, except the 6V6, are all loctals and I had to scrape every single pin of every single tube - all tested bad first due to oxidized pins.

As for Class A distortion - many audiophiles prefer Class A for small systems. Class A has a bit more of non-linearity but then has no crossover. Pick one
The filter you refer to, interestingly enough, is also present in the radio with the same model number and the letter "R" at the end and it is connected via a switch there that is only engaged when in FM mode.
Which tells me it could be used at higher frequencies. Since it is a series resonant filter and will at the resonant frequency become a 100 Ohm resistor (the frequency is unknown as I have no inductor's data) I think it might be used to compensate the fact that the impedance of the speaker-transformer system rises with frequency and with FM giving us 15kHz could exceed the optimal value somewhat upsetting the power transfer, so they tried to lower it somewhat by paralleling a 100 Ohm resistor at higher frequencies.