Hi-Fi Tone Control
This is a cheap high fidelity (hi-fi) tone control circuit. The schematic is one channel (mono) tone control, build the similar circuit will make it become stereo.
Use good component (such as metalfilm resistors, MKM capacitors, tantalum capacitors, good cable quality) and stabilized power supply for better sound quality output.
The quality of component, cabling and power supply will affect the quality of the output.