I would be very careful with leaving the speakers connected if you are doing this with a test tone! I've done it with the speakers connected before but I'll usually have an oscilloscope and a volt meter hooked up while doing the testing.idling the truck runs around 14.2 just went check it with my meter. Sorry for the lack of info. Can i leave my speakers hooked and just slowly ease the gain up that why I know the right load is on it.