Heres a couple of ways I use to a/b sounds 1: if you hit the FX button, the plugin window has the plugins listed down the left side, you can toggle the fx on/off using the tick box to the left of each plugin. I use this the most becauce you can work easly on any of the plugins you have loaded ( on that track ) all from the same window. 2: In the mcp you can toggle fx on/off by holding down shift and clicking on the plugin in the insert area. Or you can use the button ( thats just under & is part off the FX button ) to toggle on/off all the fx in the insert area. You probably knew this already, but just in case. :) Hope that helps Cheers