Do I need those "tweeters" if im keeping my existing speakers? Their JBL so i figured i wouldnt replace them. I saw some amps priced around $150 and under and i think they some of them were like 100 watts (and some were like 75-50). They were brand names like Jenson and Kenwood so that seemed like a good deal. But they were 2-channel. What does this mean. Do I need, for purely quality and not amazing quality, a 2-channel or multi-channel? Is their a big difference between a 75 watt and 100 watt (enough where ill spend an extra $50-$100 bucks on it?)