The Cube GX series has two amp channels and an additional preset that is saved internally, called the SOLO channel.
The way the JC Clean and Lead channels work is the same as many other amps. You turn the knobs and what you see is what you get.
The difference with the SOLO channel, is that to store a third sound into it, you temporarily change the settings of either the JC Clean or Lead channels to the settings you want, and then save that setting into the Solo channel Memory by pressing and holding the SOLO button until it flashes rapidly. The LED will then light up and go solid.
At this point the sound is saved to the SOLO channel Memory. Then the last thing you need to do is to put the settings for the JC Clean or Lead channel BACK to where they were before you made changes. This lets you hear the difference between the SOLO channel and JC CLean/Lead channels.
Here are the steps in list format:
1. Set JC Clean and LEAD channels to the desired settings.
2. Choose either JC Clean or LEAD channel as the channel you will use to create
your SOLO tone.
3. Turn the Cube GX's knobs to the desired settings to create your SOLO tone.
4. Save your SOLO Memory by pressing and holding the SOLO button until it flashes
rapidly and then goes solid.
5. Then change the JC Clean or Lead channel BACK to the original settings you used
before configuring the SOLO preset sound.
At this point, you can recall the SOLO preset by pressing the SOLO button once to select the SOLO channel.
You can also select all three channel sounds with your foot using the GA-FC footswitch.
http://www.rolandus.com/products/ga-fc/