Actually, only MIDI data can be looped. I think Phantom was referring to an AUDIO loop.
Although you can put .WAV audio up on the multipads, it is one shot only, AFAIK.
It is one of the things (along with a very limited selection of audio styles and no easy way to load new ones in quickly, or create your own) that make me think Yamaha rushed out the audio stuff for the PSR series. Without such simple ideas as letting the audio loop in sync with the arranger (which the Roland's do easily), the feature is little more than a gimmick.
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An arranger is just a tool. What matters is what you build with it..!