A.Yes.
When using the external and built-in microphones simultaneously, select [Int+Ana] in [Input Select].
MIC-L of the built-in microphones becomes the channel 1 and MIC-R becomes channel 2. Connect the external microphones to analog input terminals 3/4 channels
* Note that [Int+Ana] cannot be selected when the recording sampling frequency is 192kHz.
(2010/03/29)