Here are a few things to keep in mind when connecting two subwoofers to a mono channel amp:
* Check the amplifier's specifications. Make sure that the amplifier is stable at the impedance that will be presented by the two subwoofers. The amplifier should also have enough power to drive the subwoofers to the desired listening level.
* Use a high-quality subwoofer cable. A high-quality subwoofer cable will help to ensure that the signal from the amplifier is delivered to the subwoofers without any loss or distortion.
* Connect the subwoofers in series or parallel. The way in which the subwoofers are connected will affect the total impedance load seen by the amplifier. Connecting the subwoofers in series will increase the total impedance, while connecting them in parallel will decrease the total impedance.
* Test the setup before using it. Before you turn on the amplifier, check the wiring to make sure that it is correct. You should also test the setup at a low volume level to make sure that everything is working properly.
If you have any doubts about how to connect two subwoofers to a mono channel amp, it's best to consult with a qualified car audio installer.