Are these speakers (LS-90)as good all the RT/Rti line of speakers that polk has put out. I know that probably many polksters have not had a chance to listen to them, but in my brothers system they just blew the 70 away. deeper, tighter base, and really nice highs. I know they are not SDA's but I have not heard the SDA's or the LSi15. I have heard the 9's/7's combo and they also sound sweet. My brothers 90's are driven by a Rotel RB-1080 at 200watts per @8Ohms, they really sing.