The LED meters will display the signal as you have channels set within the stereo field (positioning the PAN knob to the left will be reflected on the L meter, positioning to the right will show on the R meter, and in the middle will display in both L & R). When pushing down the SOLO button, this will remain the same. When you push the MAIN SOLO/PFL MODE button this will change. In PFL (LEVEL SET) mode, any solo channels will be in mono and only the left LED meter will display signal. Push the MODE button again to return to SOLO/NORMAL (stereo).