L1 Pro to S1 Pro
To connect an L1 Pro system to an S1 Pro system as a monitor or an extension of the loudspeaker
- Use an XLR female to 1/4 inch (6.3 mm) Tip-Ring-Sleeve to connect the L1 Pro Line Out to the S1 Pro system inputs one or two
- Set the volume on the S1 Pro system to 10:00 o'clock and then adjust to suit the application. If you see solid red on the S1 Pro system turn down the channel volume.
The L1 Pro Line Out is post-fader. That is, it is the combined signal of all inputs and ToneMatch processing, EQ and Reverb. That includes inputs, 1, 2, 3, Bluetooth, and ToneMatch Port (used for T4S/T8S ToneMatch® Mixers).
The Line Out is pre-System EQ. That is, the signal at the Line Out is flat. It is not affected by the setting of the System EQ switch. 
This applies to any L1 Pro system (L1 Pro8, L1 Pro16, L1 Pro32).