In my shop I have all dedicated 20 amp lines with $200 Furutech outlets, and quite frankly I find good power conditioning mandatory.
I use the Running Springs products and I find them to make a huge difference in my display systems.
Sound stage width is improved, image depth is improved, bass tightens up.
Audience are good, but it does depend on the model you used, the higher end units with the teflon caps are much better,
I have never liked the PS audio conditioners, or any other reqenerator.
When using a power conditioner they are very system dependent and you also must make sure the piece you use has been broken in and warmed up sufficiently.
If adding a good power conditioner is not audible it may also point to a lack of resolution, elsewhere or something which is causing you not to hear it.
Again from my experience the differences should be quite obvious. I have purchased close to $40,000.00 worth of power conditioners for my shop, and I did have to purchase them, if they did not work I wouldn't have bought them.