Amplifier pairing for Altec Flamencos

I am considering adding a new amplifier to try out in my current system and could use some advice on choices to consider that would be an upgrade and complimentary to  my setup.  I have a pair of Altec Flamencos modified with the Werner Jagusch crossovers and play them with my Don Sachs preamp and a Tubes 4 HiFi  ST 120 push pull tube amp. Listening source is Bluesound node 2i with Schiit Modi Multibit Dac.   I have also been utilizing an SVS SB 1000 with them. I am not positive that my current amp is affording the old Altecs the level of dynamics and resolution that they are capable of achieving. My normal avg listening level is 75db with peaks hitting low 90s db.  Though, on occasion, I will go to 11.   What amp will resolve this question? My budget for the amp new or used is up to $3500.