Check the setting of the SPEAKER setting on the UTILITY > CONFIG2 screen (Reference Manual, page 129).
Hope this helps -- pj
Determines whether or not the sound is output from the speaker of this instrument.
HEADPHONE SW: Speaker sounds normally, but is cut off when headphones are connected to the [PHONES] jack.
ON: Speaker sound is always on, even if headphones are connected.
OFF: Speaker sound is off. You can only hear the instrument sound via the headphones or an external device connected to the AUX OUT jacks.