I use the Korg PA300 in Church. The internal speakers have adequate volume for the room and congregation size but the bass gets absolutely lost in the room acoustics. I am desperate for any way to leave the internal speakers turned on while I am extracting an audio signal for use with a subwoofer. Adding a completely separate sound system to be carried in and out every Sunday would make the project useless.
Any help would be much appreciated.

Graham,
the PA300 does not have stereo line outputs. Only a Headphone jack so you can't use an outside system and still have the internal speakers on.