Wikipedia
IQfx
iQfx is a family of plug-ins for the RealNetworks players: RealPlayer, RealOne and RealJukebox. These plug-ins were created by QSound Labs and incorporate proprietary digital signal processing algorithms. The foundation feature common to all versions is a stereo sound stage enhancement called QXpander(R) that, according to company claims, proportionately expands the perceived width of the stereo image without undue sonic coloration (e.g. inherent bass and/or volume boosts) and without weakening the critical signal components such as vocals and bass instruments that are normally placed in the center of the mix.