To be clean in color and background, change the resistors from the sand white type to one such as MILLS Non-Inductive Wire Wound Resistors. Changing magnetic core inductors to air core inductors (will create more loss due to more turn so have to reduce resistors in same path or increase resistors in different path for loss equalization). You can also replace electrolytic to film cap. Different manufacture caps will result different characters in sound. All three will improve your problems.
