The control of volume is realized by the u32 library. The library can work in all the MS Windows versions (95, 98, ME, NT, 2000 and XP). [Commercial] http://www.dmm.cz/en/dmm_volume_dll.htm
A high-quality IT/XM/S3M player library. Versions 0.9+ will have MOD support. An add-on is available for playing OGG files. [Freeware] http://dumb.sourceforge.net/
Provides applications running on Pentium-class PCs under MS Windows 9x/NT/2000 with a MIDI-controlled, low-latency, fully programmable wavetable module implemented entirely in software. [Commercial] http://www.polyhedric.com/software/vssdk/
DRC generates digital room correction FIR filters to be used within HiFi systems in conjunction with real time convolution engines like BruteFIR. [Aladdin Free Public License (AFPL)] http://freshmeat.net/projects/drc/?topic_id=114
An audio system with network support and provides the ability to use stereo, 3D audio, doppler effects, music playing (MIDI, HMP, MUS), and cd playing and ejecting/changing. [Open source, BSD License] http://gsi.sourceforge.net/