i am interested in using the 5.1 ultras in a 4.1 type setup. I will take the l/r rca from my tv and split it so it gives signal to both the front l/r and rear l/r speakers. My question is, will this eliminate the subwoofer completely? Does the sub onlywork if it recieves signal from the center/sub signal or will it just use a crossover on the 2 channels to produce bass?