Also das wäre mir neu...zumindest das S55 kann das nicht soviel ich weiss. Midi & MMF geht.
wav to mmf converter:
http://smaf-yamaha.com/tools/dl/WSC-MA2-SMAF-u.zip
For creating SMAF using WSC-MA2, it is necessary to prepare WAVE file (*.wav) which fulfills the following conditions:
Sampling Frequency : 8kHz or 4kHz
Sampling Bit number : 16 bit
Channel number : 1 (mono)
File size : 100KB or less