Mike, I have recently done an extended test of 3 power conditioners side-by-side. They consisted of the Niagara 5000, Denali 6000 and the Ansuz power conditioners. As you mentioned, I did experience a hum in the Niagara 5000, which I found disturbing. While it did improve dynamics and bass extension, to me it seemed to veil the music a bit. The Denali was more transparent and did not seem to cloud the presentation as much as the Niagara. Ultimately, I chose the Ansuz line as it presented the cleanest, most transparent sound. It is worth mentioning that I use a Hegel SS amp and my speakers are fairly efficient at 93db. I started with the entry level Ansuz X series conditioner and an Alum power cord from my outlet and an X cable from the conditioner to my amp. The Ansuz line seems to perform best when you use their cables. I started with the entry level as I wanted to limit my investment and live with it long term to ensure that I was on the right path. I have been using it now for a few months and very pleased. I can see myself upgrading to their higher end models in the future. I hope this was helpful.