To be honest, there is nothing complicated about this setup at all. With some basic signal flow knowledge, the manual, and some light googling to fill in some gaps, everything I'm about to show can be figured out fairly easily. But since I personally couldn't find instructions for this specific setup in a single place on google, I might as well do a quick write up so it exists for whomever has the need for it in the future!
What you'll need:
1. Two 3.5mm to 3.5mm cables. You probably already own some. If not, you can find an example of which ones I'm talking about here!
2. Sound Devices Mixpre-D with two working AA batteries inside.
3. Sony PCM M10 with two working AA batteries inside.
Ok, let's begin!
I. Grab one of the 3.5mm cables and plug one end into the Tape Out jack on the left side of the Mixpre-D, and the other end into the Line In of the M10, as pictured:
II. Grab the other 3.5mm cable and plug one end into the TAPE RTN (Tape Return) jack on the right side of the Mixpre-D, and the other end into the Line Out (Headphones symbol) on the M10, as pictured:
III. Turn on the Tone Oscillator [~] on the Mixpre-D (the little sine wave) and set your M10 to REC Pause with 24-bit depth. Now calibrate the REC Level on the M10 to -20 dBFS (unity gain), which should be right below the number 5 on the M10's gain knob itself:
IV. Now that you're properly calibrated, press the headphone controller to switch between monitor sources until you see the Blue LED labeled RTN come on. This means you can plug in your headphones into the Mixpre-D instead of the M10 to monitor your input signal and your playback!
That's it, you're good to go! Properly calibrated and getting that nice headphone signal straight out of the Mixpre-D.
At this point I'm figuring out how to keep the two devices together, probably using thick rubber bands. And maybe have some tape over the gain knob on the M10 so it doesn't accidentally move. Recordings made with this rig (plus the Sennheiser MKH 8060) coming soon!
-Juan