@duegi I own both 3.6 and CS6 and my favorite all-time speaker is the 3.6 bar none. I like the CS6 but as you can see from my opening line I prefer the 3.6. They both have great bass in my room, the CS6 does go a bit deeper, sounds like a bigger speaker and will play louder. But no other speaker does it for me like the 3.6 - the coherency, dynamics, tonality, and see thru transparency is first rate. I am rocker and it plays plenty loud for me.
Maybe it’s the design as they are slightly different, the CS6 has a coaxial midrange/tweeter. It just doesn’t sound as pure as the 3.6 midrange and tweeter. Not as "you are there" for me. BTW, I am driving them with Mcintosh 501 mono’s which are beasts with plenty of current.
You can’t lose if you decide to get a pair of CS6’s - they are a hell of a bargain for the speaker you get! I do swap them in and out on occasion with the 3.6 but the latter gets much more play time. Good luck.