I never used tone controls. They are needed when the speakers or acoustics are awful. Turn down the boomy bass or shrieking highs. Turn up the mids so the voices can be heard. Feedback? Then turn down all the tone controls.
The old circuit uses very old low power opamps that are not designed for hifi. I used TL06x opamps about 35 years ago. They are very noisy (rumble and hiss) and since the operating current is as low as an awful LM324 and LM358 then they might have the same crossover distortion (distortion is not mentioned on the TL06x datasheet). This old circuit uses low noise input transistors so that the noise from the opamps is less. Why not use modern hifi opamps without the added transistors instead?