I have not experienced the variance others have reported.
I have been playing music through the system for 14 to 16 hours a day followed by a 10 to 8 hour break, though there is some draw through the outlets during the down time.
My system is highly transparent (read: resolving... mentioning this to address a point from earlier in the thread regarding low-resolving systems).
The outlets have about 220 total hours on them (as of now). Assuming 60% playtime, accounts for 132 of the total hours (an approximate figure).
May I ask if you have experienced further changes to the sound after 400 hours or so? 220 hours is quite far off the 300 hour mark where I perceived a sudden significant jump in performance with the outlet.
As echoed by others, this GTX-D NCF outlet is the best I’ve experienced in my system. I do not have the privilege of trying other premium outlets but this one combined with good power cords truly transformed my system.