from experience, a cheap system paired with a nice sub = the cheap speakers being drowned out by the sub. ive demoed that system before and it is very "boomy" and hollow sounding. i would think if a sub was added, it would just throw the bad sound off kilter and make it sound worse. and there is no way that system can pump no 380w of power because i highly doubt those speakers included even have enough xmax to handle it. not to mention even a moderatley effecient speaker system can produce deafening sound at 80wpc. i once hooked a nice KEF sub up to a cheapo RCA shelf system and it did exactly what i claimed it would do, sounded worse then without it.