I don't mean to overstate the obvious,but there is NO power from the output of the keyboard. It will never power any speakers. You MUST use an external amp to hear the signal over the level of the internal speakers.

At the risk of sounding overly-cautious - be sure of WHERE you plug into, BEFORE ytou EVER plug anything in. Make sure you are certain of the system operation before you attempt to connect to anyone else's gear. You take a risk of ruining BOITH systems if you are not familiar with different gear set ups. Be careful, my friend. The lights on the tree should be the ONLY thing burning at this party !