Using the Multi-Channel Arpeggiator

1. Set up your MIDI keyboard to output on multiple MIDI channels (e.g., 1, 2, 3).
2. Put Audity 2000 into Multi mode (MIDI Mode page in Master menu).
3. From the main screen, turn the arpeggiator 'on' for the desired MIDI channels (e.g., 1 and 2) and select different presets for each.
4. Start playing.

Source: Audity 2000 — audity-2000 (manual)