One way do solve that, assuming a single-ended input, is to wire the input circuits of the two channels as a single differential amplifier- with each output then driving their respective channels. This assumes a discrete solid state circuit. And you might need a negative power supply to make it happen.
Another way would be to use an line transformer driving the two inputs. This is by far the easiest way to do this but the transformers that are worth it aren't cheap. Jensen makes the best- its either that or Lundahl. If the secondary driving the input of the EQ has a center tap that would be helpful, but a pair of resistors would do as well. PM me if you need more info.