PS Audio Stellar P3 Vs Audioquest Niagara 3000

It seems like everyone have different preferences but these two brands are often compared to each other. I also keep on hearing that PS Audio Regenerator can limit dynamics to the point of music feeling like wall instead of 3D layers and Niagara can introduce inaudible hum?

Unfortunately there is no way I can audition both because most dealers only have lower end stuffs for demo, all of my gears are bought blind with no audition. Can anyone explain why I should choose one over the other based on my system listed above? I don’t have the Audioquest Thunder PC yet but Thunder is the only one on that range that my dealer have enough (4 pcs) on stock so I am going to get Thunder for sure. Thanks !!

My problem is that my systems while hyper realistic and nice warm sounding is veiled and not ‘forward enough’.... I know my components are still breaking in (80 hrs today) but I also know that the system will not magically reveal everything like I expected after the break in is done. Piano, trumpet, guitars, cymbals, violin and drums while sounding very very realistic are way too tame and lack authority. When Santana is showing off his skill, his strings sounds realistic but weak with absence of authority. 
Again system as follow; MC75 amps, Bartok streamer/dac, SF Guarneri Evo, Cardas Clear Reflections speakers and XLR cables. Need to complete PC and conditioners and also C22 pre amp as I am not running pre amp yet. Right now I am still on stock power cords and cheap plastic computer power distributor. 

What would you guys suggest based on my descriptions above?? Or perhaps I should spend the money on pre amp first before upgrading PC and conditioner? Please advise and many thanks!! 

Inserting a good preamp will most certainly help in dynamic and musical involvement (though no experience with said Mac C22).
PSA regenerators as well^, but PPP model and above. Even so, lumping front ends together with amp/s is not advisable when possible ime.. Sound can then get a tad constricted/mushy (dynamic and separation suffer) at higher volumes—even with their P20.
So, ideally two separate dedicated 20A lines plus two regenerators.
But once dialed in (with right setting of Sine/MW strength and correct application~what gets plug where etc) there’s no going back.
I understand you have ‘stable’ grid, however again ime ymmv, a variance of just 2-3V (under/over voltage) is enough to turn one pleasant session into a headache inducing one.
Long time happy PSA user here, have tried many other offerings (some much costlier) but ultimately back to PSA, as I find having stabilized voltage is one key aspect to my many great listening sessions.
Btw.I found Shunyata HC/XC series power cables to work well with PSA regens.
For signal cabling try Siltech, for your system and sound goals—I think a pretty good match.🍻