Isn’t the Gold Note output impedance very similar to the Herron’s?First, as I mentioned earlier, while the manual for the Gold Note states 500 ohms, two other references provided at its website indicate 50 ohms.
But in any event, and assuming the Gold Note is purchased without the optional tube-based output stage, even if its nominal output impedance is 500 ohms it probably doesn’t vary greatly from that value over the frequency range, given that it is a solid state design. But like most tube-based phono stages and preamps the Herron almost certainly uses a coupling capacitor at its output, which most likely causes its output impedance to rise to considerably higher values at deep bass frequencies than the nominal value that is spec’d (which in turn is most likely based on a mid-range frequency such as 1 kHz).
I’ll say also that I’m not at all surprised at the sincerity and excellence of the response Keith provided. As I know many others here would agree, one couldn’t hope to find an audio designer/manufacturer more wonderful to deal with.
Best regards,
-- Al