All variants of SmartAmp feature the same rear panel layout with the exception of the input and output channels. The SmartAmp 10 features two input and outputs, while the SmartAmp 20 & 30 feature four input and outputs.
Further details on each section can be found elsewhere in the Help Centre from the articles below
Maintenance - Updating SmartAmp Firmware
DIP - Dip Switch Preset Guide
GPIO - General Purpose In/Out Connections
Input Connections
Loudspeaker Outputs
SmartAmp 10
SmartAmp 20 & SmartAmp 30