The stereo sockets on the back of your keyboard are there for a reason....
You should have no trouble connecting your XP-60 to a Hi-Fi. Just watch the output level of your keyboard, turn down you master volume. Then adjust it to the required amount.
Hi-Fi inputs are designed for a signal level of around -10dBu, your keyboard can generate higher levels, so you could overload your Hi-Fi's inputs, so bare that in mind.
NOTE!! DO NOT USE THE INPUTS MARKED PHONO - You get serious distortion if you do.
Input's for Aux, or Video, or even a spare Tape in should work fine.
You'll need twin 0.25" mono jacks for your stereo output from your XP-60, make sure the cable is screened, and the lead should terminate with phono connectors for your amp.
If you need additional help, just ask.
The keyboard cannot get messed up by connected anything out of it. MIDI in that's different......
Perhaps it's time to start looking for a small mixing desk!
_________________________
The Sonic Energy Authority - a sound investment