Here's a very simple tone-control circuit. Low and Highs, baxandall config.
Usually works well.
The 741 is not quite an audiophile quality type, replace with an TL72 or an OPA.....
But idea is same.
The opamp can act as a pre-amp too, of course, with the right feedback.
(play with some resistor values, but NOT with R5/R6!)