Rubidium Clock

Can anyone advise whether an Esoteric Rubidium clock would improve the sound on my Esoteric X-01/D2 player? I have been told "not much since it is a one box." But the reviews have seemed to indicate that the upgrade in sound quality is quite apparent. I am aware that some upgrades are very small in their ability to be heard, others are like a whole new piece of gear.
Any advice is appreciated.