Can anybody tell me the general design differences that these three companies are known for? For instance, Cerwin Vega and Klipsch are both known for making some of the most efficient speakers in the industry. What are their (Polk, JBL, and Infinity) niches in the industry? My experience with Polk is limited, other than that I know they are a well respected company. I've heard JBL, but only their professional (PA) products. And I've only heard Infinity's SM series back in the 90's. I would like to hear a definitive synopsis, if anybody can provide one.