I have owned the Sierra 2's and currently own and love my RAAL Towers. Just received a set of the CBM-170SE yesterday and I am floored by them. These are fantastic. Had I never owned the Towers I would have had no issues making these my main speakers. These are fantastic. They will be apart of my new small HT set up..
I have them running right now with a Martin Logan Grotto sub in my music room. All I did last night was unhook my Towers and make a slight adjustment to the setting on my Parasound P5 preamp. I have them both set to 80 on the sub/main controls.
Now there is a little mid left out on these compared to the RAAL towers and of course the highs are not as clean. However these come super close.
I would absolutely love to run the CBM's with the Rythmik Dual 8 sub to fill a little of the mid bass. Just amazed that you get this good of a sound at this cost. Ascend rocks!!!