Here is what the maual explains for X1
To use a track’s Stereo/Mono button
1. Open the Track Inspector or Console view.
2. In the track you want to force to either mono or stereo for processing effects, click the Stereo/
Mono button to the desired position:
• When the button is lit, the track streams in stereo.
• When the button is unlit, the track streams in mono. Mono audio clips may be increased by 3 dB in certain scenarios
There are some situations where the level of a mono clip will be increased by 3 dB if the track's
output interleave (mono/stereo toggle) is set to mono:
• If the track has mixed stereo and mono clips
• The track has a synth selected as its input source
• Input Echo is enabled or the track is armed for recording
In summary, whenever the track output interleave is mono and the data interleave is stereo, mono
data will be increased in level by 3 dB.