There's a newer nezplug that screws up GBS files less severely. Some GBS files that didn't work right in the old Nezplug before now work with the new one. As an example, DBZ Track 20 synchs up correctly, and the noise channel used at the loop point doesn't continue indefinately. It is a marked improvement over NEZPlug 0.9.4.8, which hasn't been updated in so long, and it's worth the effort of getting an extra download in order to get this to run. I've gotten involved in a small portion of it's development as I run into problems I understand.
Get and install the SP1 Redistribution Package, which is about 2.6 MB
"Visual C++ 2005 SP1 Redistributable Package (x86)":
Visual C++ 2005 SP1: vcredist_x86.exe
Nezplug ++ (0.9.4.8 + 2 + 19.02 upgraded version) (2010/02/13)
Homepage: http://offgao.no-ip.org/program/nezplug++.html (Japanese)
Plugin Download: nezplug__.zip
Source Download: nezplug___s.zip
The original 0.9.4.8 version's in_nez.ini file should work with the new version, so you just need to overwrite the old version of the plugin.
If you don't install the Redistributable Package, the plugin won't be recognized by Winamp, and won't appear in the list of input plugins.
Working Better: (Not neccesarily accurate, but at least better)
Chikyuu Kaihougun "ZAS" GBS (Game Boy Sound) (Works now, period)
Qix GBS (Game Boy Sound) (Sounds correct to me, as accurate as in other players apparently)
Magi-Nation GBS (Game Boy Sound) (Recently fixed, it seems)
A Boy and his Blob: Rescue of Princess Blobette GBS (Game Boy Sound) (Almost the same as the game, maybe a volume trail off difference, if that)
That's just from the list of previously error-prone GBS files. Some GBS files that weren't recognized as having problems may sound more accurate.
Also of interest is the Timer+VBlank ability that's now needed to play certain new GBSs. It's referred to as 'Use INT' in the file info box. The only functionality I know of that GBS files were lacking before this update was the ability to hook into both the 0x40 and 0x50 routines simultaneously(0x40 being the VBlank interrupt, and 0x50 being the Timer interrupt). This has now been added, and I've already used it several times to convert GBR files to GBS files, and also to rip games that I had otherwise given up on making sound correct.