Another popular way to connect an amplifier to a factory radio is to use something called a line output converter. It connects to the factory radios speaker wires and converts the speaker-level signal to a preamp-level signal. This lets you use RCA cables to run that signal to your amplifier.

How many watts is a good radio?

Most handheld two-way radios on the market today use between 0.5-5 watts of power to broadcast a signal. Some business radios are designed to run on slightly more power - between 1-5 watts depending on the model. In general, a higher wattage allows for greater range.