Note: this post is from 2006, outbound links may be broken.
GVST releases GStereo beta
From the GMulti page:
The stereo enhancement works by amplifying or diminishing the stereo information in each band. If you set a Width parameter to 0% then the associated band is collapsed to mono, which is often desirable for the bass band.
Visit GVST‘s beta page to download GStereo.