Sorry it’s an nelson pass amp involved maybe it does , or modify the fr response via its damping factor that will be very audible ( a sort of loudness effect usually)Recordings vary so wildly so using the amp as a tone control is futile use actual tone controls or EQ .
You know your getting close (IMHO) when you system sound very different with different recordings. If there is a sameness to everything even if it’s pleasant it ain’t rigth a s I see it ?
But it’s a kind of daft argument regarding the amps in question none of them seems to reach audible levels of distortion anyway![]()