We can experiment: take a test signal from anode of power amps' output tube, and feed it to input of a SS amp through a resistor of huge value, to form a voltage divider of this huge resistor and input impedance of the SS amp. I used resistor from 220V power outlet to output of a SS amp to test it's output impedance linearity.
How about something easier? Set the volume control to -6dB, then measure the distortion.
The easier to me means to stretch as wide as possible, observe, then extrapolate back to real conditions.
If people report some improvement it must have some rational explanation except boring "they prefer distortions".
a 50K pot at -20dB would have an output impedance of 850R?
Schematic shows a 10k pot feeding the amp. If you use a 50k pot, the max source Z at -20dB is about 4k, still pretty darn small.
Looking back at the schematic, wouldn't it have been better to place the volume pot before the tubes? 50K could be used there, instead of 10K after the tubes.
Probably yes.
And, I am curious, what is to use JFET buffer instead?
Intresting. I found the original buffer article with analysis, please have a look Good Design Bad Design and DIY: Entry to wonderful world of tube audio
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