First of all, I'm jealous as that's a very sweet field mixer 🙂
This is from page 6 of the user manual so my initial thought of setting the switch on CH. 1 to L and Ch. 2 to R should work but I'd send an email to Sound Devices to confirm this.
The MixPre-D is a two-output-bus mixer. Each input can be “hard panned” between the left and right output bus making it easy to use the MixPre-D in either stereo or dual-mono operations. Because dialog is often recorded in mono, each output connector can be used to send signal to separate cameras or recorders. The MixPre-D’s XLR Outputs, Tape Outputs, Stereo Unbalanced Mic Outputs,and AES Digital Output share the same program content and pan assignment.
Mike
