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.

C700 is a VSTi that loads .spc files, that might be a better way to go

Check that you've ripped them at the correct sample rate or try pitching them down.

Hi to everyone, I would like to compose music using snes sounds. I am extracing samples with snessor95, but it creates very short .wav files (max 1 second), which seems to be almost impossible to use in a sequencer such as cubase (I also use shortcircuit as sample player), because there are severe troubles with loop points so, if I want to play a long sound such as a flute, the best result I can obtain is just a "glitchy sound" that continuosly repeat itself, not smooth at all, it's not playable.

In the past I worked with cps2 samples, which were a little bit longer, so setting loop points was pretty easy and the result was quite good for most of the sounds.

I really like the idea to get exactly the sound I need from a certain game, so I would like to continue to use snessor95 or similar programs and cubase. Do you know any solution to this problem? Otherwise, do you have any advice? Thank you.