Completely agree with the "smoothing of edginess" and "enhancements in staging" but I would say that the dramatic staging improvement is most immediately noticable. I also noticed a blacker noise floor with the active shielding.
There are two major differences between the wall wart power modules & the Master Control Center. (1) With the MCC you can change AC cords, which has a definite effect on the sound. I don't have a clue about why this happens because in my mind it shouldn't have any effect at all, but it definitely does. When I borrrowed a dealer-demo MCC before ordering my own, I also borrowed every AC cord made by Synergistic. Best sonic results were achieved with their best cord, the Designer Reference Squared. It's a lot more $ but worth it.
(2) The MCC DC output modules actually have two different DC shielding voltages available; 15 volts & 30 volts (you don't have this choice with the wall warts). J1 & J2 are 30 volt active shields. J3 is a 15 volt active shield, and according to Synergistic's Scott Novak the lower voltage may work better on source components. I found that this sounded better on my CD player source, but my turntable & tuner seemed to sound the same using either voltage. Preamp to poweramp also seemed to sound the same either way.
(3) Also: the MCC offers availablilty of a second output module, allowing up to 6 pair of interconnects to be active shielded. I bought the second module also because now I have two lower-voltage shields available for experimentation, and I have a number of SR interconnects so I needed it anyway.
Overall I would recommend this active shielding system mainly for "better" rigs, where you can really appreciate the improvements. I would probably not use it for just an average quailty A/V setup.