I love Polks and have a few of the Monitor series (Monitor 5, 7, 10) but have alwys been intrigued by the Polk SDA series. I have never heard any of the SDA series and, when researching them, it is confusing because there are so many different SDA models. Can someone explain which SDA models are considered the best? I have seen the SDA SRS 1.2 listed for big bucks. Is that the top of the line model? What other SDAs would be among the better ones? Thanks.