Does anyone notice a reduction in sound quality when a tuner is part of ther audio chain?

I notice that when my tuner is taken out of my audio rack/chain that the sound quality from my system is significantly better. I like the sound of my tuner but when disconnecting it I find the cd player has a much quieter overall sound.  If my tuner is attached but turned off I still find the sound quality less than if the tuner is disconnected completely. Is my best option to simply disconnect the interconnects from the tuner to the preamp when not using the tuner? Would a better preamp resolve this issue or is it a matter of  RF leakage that would happen with any preamp?