This paper describes a plug-in for the Winamp MP3 player that uses a configurable computer to provide digital special effects for audio streams. The plug-in makes use of run-time reconfiguration, modification of FPGA configuration bitstreams at run time, and context switching. The plug-in effect processor provides filters for a graphic equalizer and an echo effect. These filters are context-switched during the runtime of an application to reduce the amount of hardware required. Further, the effects embodied in the filters are changed on the fly by modifying the configuration bitstreams at runtime using the JBits API. These techniques are described in the paper and results on the performance of the application are presented.