Just a 12V power supply that you could use outside of your Explorer.
Something you could hook your headunit to, and then hook a speaker to, to check the headunits internal amp. If everything else is hooked up properly, then you mentioned maybe something was wrong with the headunit; this would answer that question.
Something you could hook your headunit to, and then hook a speaker to, to check the headunits internal amp. If everything else is hooked up properly, then you mentioned maybe something was wrong with the headunit; this would answer that question.