[Elecraft] [KX3] MIC Bias has no effect

[dmb at lightstream.net]

I'm connecting a Yamaha CM500 headset to the KX3, and find that the
microphone works properly regardless of the MIC BIAS setting (MIC BTN is
set to OFF).

As I recall, the few times I used the CM500 w/ the K3, the MIC BIAS had to
be ON or the microphone produced no output.

Any idea why the MIC BIAS setting doesn't seem to matter w/ the KX3?

73, Dale
WA8SRA