I'm connecting a GT-series multieffects unit to the CUBE-30. Which of the CUBE-30's jacks should I connect to, and what settings should I make?

On the CUBE-15/CUBE-30/CUBE-30 BASS/AC-60, can I apply the internal effect to signals coming in the external input jack (AUX IN)?

When using a multieffects unit (such as the BOSS ME- or GT-series) with a CUBE-series amp, which amp channel should I use?