@lalitk --
I know the Leben quite well (also the smaller sibling, the CS300), and it’s a fine amp. I might try and look for a used pair of WLM Diva’s (the floor standing model as an outset), which are very good speakers built around a 10" coaxial driver with a stated 97dB sensitivity. At the time I heard them over the Almarro 318B amp, a lovely pairing, and my guess is the Diva’s will mate well the CS600X. Being a single point source per channel you’ll also be able to sit fairly close to the speakers and still have excellent summation. To boot: with their slender and finely veneered shape they're nice on the eyes, I find.