To add more emitter outputs for your existing system you will need to purchase 3 components. One is the IR-4180 bypass cable, next is the IR-1203 amplified IR hub, and finally an extra IR-3002 Dual Head Emitter. Instead of attaching your existing IR-3002 dual head emitter to the IR-4000 directly, you would use the IR-4180 bypass cable plugged into where the IR-3002 was, directly linking the IR-4000 to the IR-1203. The IR-1203 has 4 emitter outputs, which can all support dual head emitters. When assembled in this way you can support more emitters/devices for your application.