I want to replace my headunit with a nice aftermarket one. I'm trying to decide whether to spend the money on an adapter so I can just use the Bose speakers and save time and money, or to just put in an all new system with better speakers. I don't listen at truly high volumes but I do crank it up and don't want to worry about blowing the Boses.

So 1. how good are the Bose speakers (power, quality, and blow-out resistance) and 2. how much would I expect to pay for 4 better quality speakers?