Don't know if you own a Yamaha PSR A3000, but congratulations if you do. Yamaha manufactures the finest range of arranger keyboards in the world, with the best support and reliability. The A3000 has similar top features as my Tyros 5.
To answer your question, you cannot loop wave files if loaded to an Audio Multipad (audio link). Having stated that, not all is lost. You can however, load a wave file to the A3000 Audio Recorder/Player and loop it there. In addition, you can also set repeat markers to loop certain section, plus pitch and time stretch capabilities. Very powerful features, that would most likely would give you the results you are after.
Here is more detailed info, plus check out the photo of the A3000 Audio Recorder/Player interface as seen from the screen.
Playing the Audio Link Multi Pads
You can play the Multi Pad to which the audio file is assigned
by selecting them in the USER or USB tab of the Multi Pad
Bank Selection display. Although you can play them via the same operations in page 76, note the following limitations.
Make sure to connect the USB flash drive including the corresponding audio files (WAV).
Automatic repeat playback is not available.
Only one Pad can be played back at once.
Chord Match cannot be applied.
PSR-A3000 USB Audio Player/Recorder Playing Back and Recording Audio Files
The convenient USB Audio Player/Recorder function allows you to play back audio files (WAV or MP3) saved to a USB flash drive directly from the instrument. Moreover, since you can record your performances and recordings as audio files (WAV)
to a USB flash drive, it is possible to play back the files on computer, share them with your friends, and record your own CDs to enjoy as well.
You can play back audio files saved to the USB flash drive in the following formats.
WAV......44.1 kHz sample rate, 16 bit resolution, stereo
MP3......MPEG-1 Audio Layer-3: 44.1/48.0 kHz sample rate, 64 320 kbps with
variable bit rate, mono/stereo
A-B Repeat Playback
The specified section (between the A and B points) can be played back repeatedly.
1. To set the A point, press the [C] button when playback reaches to the desired point.
The time set as the A point is shown in at A [--:--] in the display, and is indicated
by the first wedge mark in the playback progress bar.
2. To set the B point, press the [C] button again when playback reaches to the desired point. The time set as the B point is shown in at B [--:--] in the display, and is indicated by the second wedge mark in the playback progress bar. The specified A-B section of the audio file will now play back repeatedly.
3. To cancel Repeat playback, press the [C] button again.
Adjusts the playback speed by stretching/compressing the audio, compared to an original
speed of 100%. Higher values result in a faster tempo.
The value can be adjusted from 70% to 160%.
Time Stretch cannot be applied to MP3 files of 48.0 kHz sample rate.
Shifts the pitch between -12 and 12 in semitone steps.
Pitch Shift cannot be applied to MP3 files of 48.0 kHz sample rate.
Cancels or attenuates the center position of the stereo sound. This lets you sing karaoke
style with just instrumental backing, since the vocal sound is usually at the center of the stereo image in most recordings.
Total playback time Elapsed playback time
Hope the info helps.