George, I agree with you. Wow, I think this is a first! My tube preamp has an output impedance much like Almarg outlined. Can go as high as 4k etc.....
I have run it with all kinds of amps with as low as 22k input impedances with no issues at all. Seems this whole thing of a 10 to 1 rule is really not hard and fast. My experience indicates it is not really that helpful. My last solid state amp had a 22k input impedance and my 4k output impedance preamp sounded fantastic with it with no roll off at all. Also, the output cap's value was a low .47uf again with no issue or bass loss.
Just my actual experiences. Others own the same preamp and with amps that have 20-40k input impedances with no issue. Pass Labs and Nuforce amps....
This question comes up often and the answers with the ratios have puzzled me of late simply based on my and others experience.
I have run it with all kinds of amps with as low as 22k input impedances with no issues at all. Seems this whole thing of a 10 to 1 rule is really not hard and fast. My experience indicates it is not really that helpful. My last solid state amp had a 22k input impedance and my 4k output impedance preamp sounded fantastic with it with no roll off at all. Also, the output cap's value was a low .47uf again with no issue or bass loss.
Just my actual experiences. Others own the same preamp and with amps that have 20-40k input impedances with no issue. Pass Labs and Nuforce amps....
This question comes up often and the answers with the ratios have puzzled me of late simply based on my and others experience.