From the ALSA wiki
Soundfont Loading with sfxload
sfxload loads a soundfont onto ALSA's OSS emulation of the emux wavetable. The new version asfxload works only with ALSA's native emux wavetable. See the SoundfontHandling page for details of how to use soundfonts.
Examine sfxload's success with -v (verbosity).
sfxload <sfbank.file> used to successfully load a sound bank which could then be used by an application like pmidi. This is the first option for sfxload, and the man page says that: The first usage is to read SF2 (or SBK) file and transfer to the awe driver. In this case, the samples which were loaded on the driver are replaced with the new one.
Then it stopped working. pmidi would play the file and the events could be viewed with aseqview but there would be no sound! When loading the sfbank.file with the above command line, -v would show that the default soundbank was -1. I discovered that sfxload <sfbank.file> needed to be told which bank to load.
sfxload -b# <sfbank.file> In the second case, sfxload reads the file and appends it to the pre-loaded samples on the driver with specified bank number. The old samples remain in the driver. The additional samples can be cleared with the -x option.
This additional flag may be necessary because the ALSA driver no longer properly handles the first case. -G. Baum, 2004-01-01
cat /proc/asound/card?/wavetableD? to see if sfxload worked (it should say something about memory and instruments). If you cat before and after the call to sfxload, it should be very obvious whether or not the load actually succeeded. -Hawkeye Parker, 2004-02-19