I love this utility, but it can take a bit of unravelling the first
few times you use it
1. Click on the 'Settings' button at top left, then on the Calibrate tab of the window
that pops up.
2. Now enter 'Volts' and 'RMS' in the Units box.
3. Next, make sure that 'Level of known input signal (units)' is 1.0
Click on the 'Start measure signal (L)' to pick up the output from your trusty Levell
5. Finally, tick the 'Apply calibration left channel' box to
calibrate Visual Analyser to this input signal.
Hope this helps!