Ok, I tried C700 and it is far better than using wav files. Very good advice, thank you.
Basically I followed these instructions
http://www.smwcentral.net/?p=viewthread&t=65193
but there's no need to convert from hex to decimal and do all those steps, everything can be done much faster.
I search the .spc on www.snesmusic.org, then open a spc player and see which instruments are playing in a piece (the .spc file). Then I load that .spc file into C700, scroll the instruments (32 instruments, many of them are just noise) and save the one I need, with the possibility to edit ADSR and other stuff.
Once the samples are saved into an archive they are ready to be used in the future with the stored settings, very good sounding and easy to recall too.