Thiel 3.6 s and amplifier choices

I recently purchased Thiel 3.6's. Currently driving them with an Aragon 4004 Mark II. Other equip is Arcam FMJ23 Cd, VPI TNT, and Krell KRSII preamp, FMS Grey cables and old Audioquest Interconnects. Looking for suggestions on amplifier as I think there is a lot more to be had out of these speakers. Balance is slightly tipped up due to mid bass leanness but they do so many things right. Any thoughts.