I have found, in my audio system, that there are places E-Mats work and don't work (or negatively work). If I can tell the difference in effect, they must do something. I have a dozen and find them most positively effective placed on power panels and isolation transformers. Next on my tube pre-amp and phono pre-amp. I have found that they negatively impact the sound placed on my new DAC and have no apparent effect on my large mono-block tube amps. There is a limit in what I can spend at this time, so I haven't purchased the gate. The Stop-Its are reasonably priced which are my next purchase. SR's small products (fuses, duplex outlets and HFTs) have been a huge success in my system and room at affordable cost. There Black Box was a failure wherever I placed it in the room. From the above experience, I doubt anyone would find me believing in snake oil or having human frailty of emotional facilities which blind me to the truth. The truth is in my experience. Other audiophiles will find the same or different truths as each audio system and room are different; hence, trial and error method in the use of tweaks. 90 day money back guarantee from PPT and 30 day from SR certainly make it enticing to try their audio tweaks.