The wrapper can work with 16, 24 and 32-bit integer audio data, but most Winamp DSP plugins only support 16-bit.
... when I put the volume slider to full right, I get clipping and when set to full left, there is still volume, and it should be mute, right ? So is this plugin even working is what I'm wondering.
Well, there are no labels on the sliders, so left may be intended not to be zero. Do you hear a difference between different positions on the slider? If so, then the plugin is doing something.