That never stopped me from splitting the single channel into separate channels with the flip of a switch using my audio interface. Single channel audio coming in through a single XLR plug instantly becomes two channels when you flip the switch that says stereo/mono.
Keep in mind the ohms rateing of speaker and radio requirements..Its likely that the big wilson chrome speaker ya got has a different ohm rateing that the ext speaker jack is ment for...I noticed the wildon changed tone and clairity as compared to the cobra highgear i use...I liked the sound of that over the wilson and even the brearcat 20..Plus the ohms rateing matched radio requirements..