One reason why the output impedance spec is important. Most amps these days are voltage-drive and as such I can't agree that the response changes "substantially" with the load.
As you say this is not the case so much with valve amps, but then who would want one of those? Ahh, someone who likes some colouration in the sound!
As you say this is not the case so much with valve amps, but then who would want one of those? Ahh, someone who likes some colouration in the sound!