Itching for better sound

Thanks for the suggestion.  I will look into that.  What do figure would be the best way to connect these to the Marantz CD6006?  Optical?  The cable's going to be about 40ft.

Do others agree that this is going to get me better sound than the setup described above?

Maybe you need to go to Itchycoo Park. 

40' may be a long run for optical + you don't know if the dac in your cdp sounds better than the one in the powered speakers, so i'd try rca as well and compare

Your receiver really will be a limiting factor with whatever speakers you choose. The Klipsch are very sensitive and your receiver will drive them. The KEF LS50 requires a good amp with sufficient power to get the best out of them. These speakers have a different sonic signature and I would suggest you listen to them to see which you prefer. 

A speaker at the $500 price point that I would suggest is the Wharfedale Denton 80th. They are available online and you can return them if you don't like them. I actually preferred them over the KEF LS50 and I am a long time KEF fan currently running several different KEF speakers in 3 systems. 

I haven't heard one, but the latest Outlaw Audio RR2160 Stereo Receiver at $850 gets great reviews.  May be your biggest bang for the buck and tie what you already have together.