The on/off switch is really made for live performances with many mics... some of which aren't used the whole time. Say you have a back up vocalist in one song... you obviously don't need an extra mic on the entire time. Since mics will pickup any sound..... They may pickup extra noise or layer the guitar sounds from the amp in the PA... cluttering the mix in the PA. That's generally what the on/off switches are there for... but in a home application or small rig... they're not needed... Most small setups don't need them either... They can be handy in recording also... but they're largely uneccessary for anyone that doesn't have a big live rig.