You can assign the Song playback signal in the TD-50 to the PHONES output only. Doing this will prevent the sound of a song from passing through to the Master or Direct outputs, or to the USB output. Here's how to set it:
1. Press the SETUP button.
2. Press the PAGE UP button to confirm that you're on PAGE 1 ("1 SETUP 1").
3. Press the F1 button (OUTPUT).
4. Press PAGE UP or DOWN to select page 2 ("OTHER OUTPUT").
5. Press F1 (MASTER).
6. Press the cursor right button to highlight "SONG."
7. Turn the dial counterclockwise to move the indicator to the PHONES 'line' only.
8. Press the KIT button when you're finished. The new setting is saved automatically.