Setup Multi-Timbral Mode

1. Press the Master button.
2. Scroll to the MIDI MODE screen.
3. Set the mode to Multi.
4. Scroll to MIDI Enable and turn On the channels you wish to use (turn off unused channels).
5. Press the Master button to exit.
6. On the Main screen, use the cursor to select the desired MIDI channel and assign a Preset to each.

Source: Planet Phatt — e-mu-planet-phatt-operation-manual (manual)