Produce audio data by opening Soundfont2 audio file container format. There three available controls, preset and instrument to navigate within container format and a open button to read Soundfont2 files and assign the selected instrument to the input.
The ffplayer contains recently the bridge widget. You can add plugins in bulk mode by click Add or Remove within AgsFFPlayer's bridge, what you can collapse/expand. To add an effect to a line, you have open as usual input/output of machine properties.