Half Insert
To connect an effects processor in parallel with the original signal you can half-insert a normal 1/4" plug into the PS1 Power Stand (Classic) / Model I insert jack (that means insert to the first “click” but not all the way) and connect that to the input of your effects processor. The output can be returned into either Channel 3 or Channel 4 in the power stand. If you want to hook-up more than one effects processor in parallel you may need to add a small mixer to your system.