I think you want EQ or tone controls. Cables to do the job of an EQ is a piss poor work around IMHO.
Buuuuttt...if you must, what you want is a design that adds slightly higher capacitance than what is normal. Shielded cables would be a good thing here. I am speaking of IC's of course. Hint: star quad geometry is 1.5 times the capacitance per unit of length than twisted pair, which is higher than coax (sometimes).