The Unofficial Sibelius Wiki - your source for tips and tricks to the worlds very best music notation software!
06/09/2010 - SIBELIUS 6.2 - WIKI software updated - Announcements

Sound sets

A sound set (soundset) is a file that lists all of the sounds available on a particular MIDI device or virtual instrument, and tells Sibelius what real instrumental sounds those sounds correspond to, so that Sibelius can automatically make the best possible use of them.

Some sound sets such as EWQLSO have been created by Jonathan Loving can be downloaded at his site http://jonathanloving.googlepages.com/