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.

You mentioned something about the HDPlex LPS, do you think it would be possible for Cybershaft to manufacture a unit to accept the power from the HDPlex.
I just contacted Cybershaft and mentioned that I have a few HDPlex LPS units laying around and I'm looking for recommendations for a 10MHz clock for my pair of Grandioso D1.
Hopefully I will hear back soon on the matter.
Ysound: you must have a very nice setup with the Grandioso gear!  For clarity, are you looking to add 10Mhz (50-ohm) clocking externally to baseline the MCL circuits in your D1s? If so, the Cybershaft is definitely worth considering....

To your question: I have no idea whether Cybershaft would produce a unit that takes a DC XLR 5-pin connector (like Wavelet) and would allow you to use an outboard power supply.  That would be a question to send to them directly.  I can tell you that with the power supply that is my the clock I purchased to begin with (designed by Cybershaft for best match and optimal performance), I've never sonically felt a need to look into this path for my setup here. The power supplies in the Cybershaft upper-line clocks are of excellent quality from what I hear out of my system.
Yes, I'm looking to add a external clock to the D1s and then output the clock signal from the D1 to the RedNet D16.
BTW, the RedNet is the real deal, just replaced my USB set up and was amazed of the immediate improvement in SQ, worth every pennies in my opinion. 
Next up, will trying out some of AQ crazy priced CAT6 cables.

ysound - I'll second your recommendation of the RedNet. I also have a D16 and love it.

Zephyr - the Cybershaft is going into an Antelope Liveclock which is then feeding the above mentioned RedNet D16 and a Mutec MC-3+ USB reclocker. I've been very pleased with the outcome.