What are the differences with the SDA-1C and the SDA SRS 2 speakers. I believe the SRS speakers are 4 ohms, I am not sure what ohms the SDA 1C's are. Is there much difference in sound quality. The SRS speaker is rated at 750 and the SDA is 500 I believe. Does anyone have both sets of speakers and how would the sound quality compare. Is the SRS much of an upgrade over the SDA 1C.