Power Conditioner, which of these 4 and why?

PS Audio power 15 generator really a power amp. Had the Audioquest Niagara 5000 traded it in for the PS audio unit.

Takes much out much more THD without 
robbing my system if it’s sound like the Niagara did. (In my opinion the 5000 was a very expensive surge protector 

I just bought the Isotek Aquarius.  I like it very much.  I have a Bryston 14bsst amp, a deHavilland preamp and a Wadia 581. Dead quiet soundstage, sparkling highs and nice bass.  The Isotek runs cool to the touch.  I solid investment for me personally.  I will soon add a couple of streaming/DAC devices to it.  

If you’re able to step up your game, I highly recommend Gigawatt. I own the new PowerPrime. 

I just returned from RMAF and noticed many of the high end rooms were running Gigawatt products. 

I had some. ((Bybees x 2), Acoustic Revive, PS Audio...)The one that beats them all in MY system is the Torus.