This is always a dangerous topic on an audiophile forum😄 Recently, I have noticed a trend in both of the rags I read for Reviewer's reference sytems to include the AQ Niagara 5000. Maybe it is advertising dollars or a better loaner program, but there it is along side all of the other best products. I recently added one to my new system (Moon Evolution Series stack, mono blocks, 802's and a stereo pair of REL 812's) and there was an immediate, obvious, improvement. I was surprised that the subs were the first thing I noticed. More speed, power at the same volume. I also noticed improvements with the transients and openness of the system. With all the new power cables (Mostly mid-level AQ stuff) and the $5000.00 unit it was about $7000.00 invested in power conditioning...a little less than one Moon component😄 Was it worth it? Well, marginal gains are expensive in this sport, but it easily added as much improvement as one of the Moon pieces! IMHO