Sandy Gross the designer of the speakers used a tube amp in his personal system. They sounded fantastic with tubes.
Sandy is a customer of ours.
The Khartago, while wholly competent, has long since since been bypassed by the rest of my gear. Looking for something with some synergy with the Primaluna.
Budget $5-7k. Been researching feverishly but it is difficult to get an audition
There are class D amplifiers now that are quite a step forward from the typical solid state- combining the speed and detail of solid state with the smoothness and involving character of the best tube amps, that fall within your budget.