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.
impedance matching amp/preamp
My amp is late 80's McIntosh 2250 solid state. My pre amp is a modified Ming Da... Impedance is way off, even though I think it has a very good sound. Amp input 50K the preamp outputs 100k which is totally backwards from all I read on the net. I have also used an AudioResearch preamp that was close in ohms, and my Onkyo AV receiver that also matches up with the amp. Neither sound as good as the Ming Da. My queston is how important is impedance matching and what am I missing.?