Groenlykke, congratulations on your CS-600 purchase. It's a very special and versatile amp tobesure. Curious as to which model of Harbeth's you were thinking of; and how big is your room?
There are many write ups on the pairing of the Leben CS-600 with ProAc's D2. I can attest, it's a match made in heaven, and with the RS-30EQ Phono Pre-amp it sings as an analog front end.
The D2's allow for easy room placement; tight bass; sweet mids and highs (roll tubes to your tastes) and the ability to handle any and all music you throw at it equally well.