SoundFX naturally offers functionallity for recording own sounds. This window offers the following functions :

gadget	description
audiomode	choose an audiomode for recording.
record-source	a list of available recording sources.
record-gain	for adjusting the record gain.
record-auto	This is a special feature of SoundFX. Move the gain to full right and activate 'Auto'. Now SoundFX will lower the gain continuosly, until it does not clip anymore.
monitor-source	a list of monitor-outputs .
monitor-gain	for adjusting the monitor volume.
levelmeter	These levelmeters show the volume of the input signal. The red bars mark the maximum value. The values to the right of the meters show the current input and maximum.
reset	for resetting the maximum-display.

A click on "Record" obviously starts recording, where a click on "Stop" ends it.