Just about any speaker you like. The electronics are not limiting your choices. Based on your musical taste, I would seriously consider the Merlin VSM-MXe. I think Ken likes Merlin, Avalon, and Wilson. Ken has Merlins at the factory and has been at shows with them. For small scale, acoustic music there are few better speakers made. I don't like making across the board recommendations, but the Merlin VSM-MXe would likely make you very happy with the CATs - I was.
Speakers to Match to CAT pre amp and CAT mono bloc
The musicality and dynamics of CAT amplification is legend. I would like to know, from those that have CAT amplifications, what speakers would you recommend for a room that is 25'L 17'W x 13'T. Music library is principally jazz (acoustical,vocals, small ensembles) blues, and world music.