I was contemplating purchase either of these; with the preference as stated below 1>20-39 PCi 2>25-31 PC-Plus 3>20-39 PC-Plus I Plan to use it in a 3000-4500 CB Ft Room at moderate listening Levels. I wanted to know the differences between these models w.r.t. to THD, Frequency Response, and tightness of bass. I know that 20-39 PC Plus can go much below 25-31 but for my room size I can compromise on the O/P power for sake of getting lower frequencies. Does the PC-Plus have any other advantages over PCi at same (moderate) listening Levels (apart from Higher wattage) due to the subwoofer being used.