D mic preamps. ie darlington technology from my checking ?
It's not really Darlington. I think the D really just stands for Discrete, meaning that it has discrete transistors at the input, rather than going straight into an OpAmp. Yamaha's description says "inverted Darlington", but that's not a correct name for what they're using. They're what I've long known as a "complementary feedback pair", though I've just learned it's also known as a "Sziklai pair" or the "Sziklai connection".
It's a configuration I'm more used to seeing in power amps, but then usually in class-B configuration. It's quite a nice configuration.