If you own an S-550, check out this utility I wrote.
It converts Wav files into Sys Ex MIDI dumps.
Go to: http://www.geocities.com/pctos550/
and click on the image to access the download page.

New in ver. 2.0:

Lots of small bugs fixed.
Stereo file support added.
Multiple sample rate support added.
On-line help support added.
Sound events added.
Faster 'convert to file' processing.
Fewer components needed to run program.

It is freeware, just drop me a line to let me know if it works for you and what you think of it.

Hope it helps.

Andy.