Pierre,
A friend of mine had a HP200 preamplifier. That is a very good unit. My only "issue" with it was the course steps for the attenuator (the ideal volume always seemed to be between two steps).
Once you are familiar with the sound of the Hovland, I would suggest looking into trying different 12AX7s in the phonostage. The "right" choice would be a matter of taste and system matching. The one that came with the unit might be ideal for you, but, you may find something else works a lot better. My friend ended up swapping the one that came with the Hovland for Amperex Bugle Boy 12AX7s--a lot more expensive, but worth it in a good sounding unit like the Hovland.