Lack of dynamics, recessed sound, and different interconnects making big differences to the tonality - are what you would expect if the ratio is too low. But you can also have problems when the ratio is too high. For example I has a ss preamp using BUF03s as an output device, and these things have vanishingly low output impedence, driving a tube amp with high input impedence and the sound was overly hyped and hard-edged. Padding down the input impedence of the tube amp improved the neutrality and overall naturalness, and fleshed the images out.
What is the Sound of Impedence Mismatch?
As I understand it, you want your power amplifier to have an input impendence much higher than the output impedence of your preamp, at least 10x. Can anyone tell me what the sonic symptoms are of a mismatch? If I'm hovering around 10x, what might I hear that would indicate an impedence mismatch as opposed to, say, a preamp that is simply too bright or whatever?