Solid State Logic SSL 12 USB Audio Interface - Manual (Page 18)

Tip:
Shift + Mouse Click sets the fader to 0 dB. Alt + Mouse Click also sets the fader to 0
dB.
7. Stereo Link
Clicking on either 'O', two sequential channels can be stereo linked and will convert
to a single fader stereo channel. When activated this 'O' will change to a green
linked symbol as shown below:
Note: These controls affect only the playback of the signal via the Monitor Bus , and
won't affect the signals recorded into your DAW.
Talkback
Routing Sections HP A Highlighted as an example