| 1 | ON | Power up C 427 from standby mode. |
| 2 | OFF | Switch C 427 to Standby mode. |
| 3 | 0-9 Number buttons | Direct entry of frequency channel or Preset number. |
| 4 | SLEEP | Set sleep mode timer. |
| 5 | MEM | Save the current station to a Preset number. |
| 6 | DEL | Delete the selected Preset number. |
| 7 | PRESET | Step up or down between Presets. |
| TUNE | Tune forward or backward. | |
| ENTER | Select Tune or Presets mode. | |
| 8 | AM | Select AM band. |
| 9 | FM | Select FM band. |
| 10 | BLEND | Activate or deactivate the BLEND feature. *The NAD BLEND feature reduces noise and hiss while retaining some level of stereo separation, instead of switching to mono. |
| 11 | FM MUTE | Activate or deactivate FM MUTE mode. |
| 12 | DIMMER | Reduce or restore the front panel display (VFD) brightness. |