impedance matching amp/preamp

Without getting into technical details, the analogy of how a drum skin works to produce sound is a good one to help understand what is going on.

A drumskin that is too loose will have less impedance to resist the strike of the drumstick which can result in a loose, distorted sound. Tightening the drumskin produces a tighter, less distorted sound. How tight the drumskin should be is a matter of taste, however there is some point at which too little tension produces poor sound quality

Eletrical impedance in a circuit is like the tension on a drumskin. it enables voltage fluctuations to register and be transferred correctly. If impedance is too low, the effect can become similar to that loose drum skin and result in higher distortion ie less accurate detection and transmission of the input signal.

Thank you for both explainations. I think I will only understand it fully when I find a way and the time to immerse myself in the Physics. I seemed to understand these concepts with much better facility thirty years ago. It is annoyingly frustrating for me to have only a dilettante's knowledge of electronics.

FWIW, I suspect that the specifications of the Ming Da suffer from "Chinglish", and that it should read output impedance 100 ohms, not 100K. Their other preamps list anywhere from 8 ohms to 600 ohms, though a couple also state 100K. It's something that would be easily overlooked by a translator.