PS Audio Stellar P3 Vs Audioquest Niagara 3000


I am sorry if this is the wrong forum, but there is no section for power conditioner/generator so I thought best to put it here. 
I like the concept of AC-DC-AC regeneration from PS Audio, but I also heard that Audioquest Niagara is a worthy opponent. Being in Indonesia, my options for what’s available immediately are very limited. I have the option to buy a Niagara 3000 for $350 more than Stellar P3, which one should I get? All power cords from wall to components are going to be Audioquest Thunder. I have a stable electrical grid. 
The rest of the system are as follow; amp Mcintosh MC75 MKIII amps, dCS Bartok streamer/DAC, Sonus Faber Guarneri Evolution speakers. 
Or should I postpone power conditioners & cable and spend money on Mcintosh C22 pre amp first? 
uwiikz
Bvdiman, thanks so much for your detailed explanation. Much appreciated. I noticed that you are a fellow Indonesian audiophile, awesome! 
I just bought C22 from Victoria Audio M2 Mall yesterday, Lukito the owner suggested me to get the pre amp first and he was right. The improvements are a lot, better separation, MUCH better staging, a lot more details and off course authority. Even my wife who thinks Bose sounds good can really tell the difference. But off course, it became even more obvious that some constraints I am still hearing are needing proper power feed for any improvement. 
I finally found the distributor for PSA product after emailing PSA USA. I will keep in touch with Ongky from Audio Image unless you know other? What you told me about separate regenerator/conditioners make a lot of sense. Especially after I booked another pair of MC75 from Victoria Audio for bi amping. What would you recommend? A pair of Stellar 3 or a pair of P12? A pair of P20 is definitely out of my budget right now as I just bought everything within this month and I don’t think my system is high end/hi power enough to warrant a P20. 
Thanks a lot! 
It might be worthwhile to change the wall outlet to Furutech GTX-D (R) NCF before going with power conditioners.
@uwikkkz Hi, yes contact/consult Mr.O..
Known him for 25yrs, bought some of my earlier stuffs off him. SF Strads, Soulution, couple of Magicos amongst others, and some nice cablings too (Kubala, Synergistic etc). Although he no longer today carries all the aforementioned brands, I just recently added a P20 through him. Good man, great service.