Some people claim to hear a difference, but I don't know how many (if any) of them made a blind test to make sure the don't just imagine it.
You could also try out_ds ssrc
set to 48kHz.
Careful though, that installer also overwrites the regular DirectSound output plugin (that may be needed for eg. 'protected' wma) with an older version. I'd back up out_ds.dll from the winamp plugins folder before running it and put it back in afterwards.