I own a Sansui AU 7700 a vintage marvel with sound controls sophisticated in design ( my knowledgeable repairman said so repairing all amplifiers for all his life) an a three tone control and other features like a separated filtering system with three other buttons to filter at different Hertz scale...
Before Acoustic treatment and control of my room i used the tone controls with success... Not now after acoustic done right i dont use them at all... Only some filtering......
At any sound level all acoustic cues are optimal for me now in my room ...
Look for some low cost acoustic improvement...Not to a new costly amplifier....
Electronical equalization is most of the times a worse way acoustic solution instead of room acoustic done right...Especially when someone EQ each of his album... 😁😊 it is a symptom of acoustic defect of his room....Then he EQ each album because EQ is a plaster on a wound not a therapeutic...And most EQ choices apply to a restricted set of albums to compensate for the speakers/room bad acoustical synergy...