From the V3 manual-
"When using the analog outputs and sending the signal to a recorder with a variable input, use
the following procedure: turn the gain control fully counter-clockwise, turn the trim control fully
counter-clockwise. Set the record level control on the recorder to 12 o’clock or midway between
minimum and maximum. With the sound source present, adjust the preamplifier gain control
clockwise until the signal peaks at –9dBFS (+16dBu) on the V3. Adjust the record level control
on the recorder for the optimum recording level."