Theater Effect Panel (EffectPanel) is small open source software used to play sounds during live performances. You can use this program for free and it can be used with a mouse, a touch panel or over a midi interface with a keyboard or a button pad.

A soundboard that supports almost all MP3s and WAVs. Sounds can be triggered with custom keyboard hot-keys and played through up to 2 outputs. i.e. Your speakers and a virtual audio cable. Also allows for your mic to pass into the virtual audio cable when enabling Mic Injector. This soundboard also incorporates a save feature.
Features:
- Easy to use soundboard app, allows soundboards to be saved.
- Use keyboard hotkeys to trigger sounds
- Play sounds through a virtual audio cable and still be able to hear them through your speakers
- Includes Mic Injector to route sound from your mic into your virtual audio cable
- Includes converter tool for converting almost any audio file into a compatible one

sourceforge.net/projects/expsoundboard
How To Use Microphone While Using Soundboard (Using Mic Injector)
Soundboard makes building / executing sound cues for theatrical performance a snap. With a mix of sound, fade, stop, pause, and resume cues, you can create elegant designs, and execute them with the simple push of a button.
- Create elegant designs using a combination of simple cue types.
- Supports popular audio formats, such as wav, mp3, and Ogg
- Written in Java for true cross-platform compatibility
- Simple to use, so you’ll have a novice operator running the show perfectly in no time.