The Roland GAIA-2 lets you change tones while the sequencer pattern is playing.
To switch tones during playback, press the [PRESET], [USER], or [MODEL] button to show the TONE LIST screen, then select a tone using the [1]-[8] (BANK) buttons and [9]-[16] (TONE) buttons.
Note: The sequence data recorded in the tone also switches. If the new tone has the same Scale and Step Length as the current one, the playback step position carries over, so the pattern stays in sync as you switch tones.