Spoon, the developer of dBpoweramp, has opened the DSP architecture for outside development.
http://forum.dbpoweramp.com/showthread.php?p=105445 (http://forum.dbpoweramp.com/showthread.php?p=105445)
DSP (or Digital Signal Processing) are effects which process the audio signal in some way, used whilst dBpoweramp Music Converter processes audio files. A classic example of an effect is a Graphic Equalizer, which will boost certain frequencies. Actions can be processed, such as deleting source files.
For a list of currently available DSPs and their functions:
http://www.dbpoweramp.com/dbpoweramp-dsp.htm (http://www.dbpoweramp.com/dbpoweramp-dsp.htm)