Not sure if any of these have been posted yet but I have a few suggestions.
1. Anti-Vibration mats work great under any vibrating components or assemblies. In my experience, even if you don't hear it from your side, vibrations may be more audible on the opposing side of a structure.
2. FURMAN makes excellent quality power conditioners. Surge protectors only filter out voltage spikes/drops above a certain threshold to protect electronics from damage. Powder conditioners "condition" the supplied electricity and reduce RFI/EMI. I have personally never used one with a Ballast or CO2 injection fuzzy logic controller, however, I do know that "noise" in terms of electronics is generally caused by non-linear loads and both ballasts and fuzzy logic controllers are non-linear loads. I used to have a Furman M-8X2 Merit Series and it worked wonders for reducing electronic noise from my PC and Studio monitors. Power conditioners definitely "work" under the right circumstances, so this might warrant some further research.
3. While not a direct noise-reduction tip, download TrueRTA. This is a free software which will allow you to analyze the frequency of any given sound. This will help you pick out the most efficient materials for sound control. Different materials interact differently with different frequencies of sound. Very dense materials are great for reducing low-frequency sound & vibrations but will not be as effective against high-frequency electronic noise.
4. A more intensive approach for larger scale setups may be active noise control. Using a similar software to the one above, the frequency is analyzed and an opposing frequency is generated with a pair of loudspeakers. This is the same way "noise canceling headphones" work. For large scale use (ie. an entire room) it's only really suitable for lower frequency noise that is repetitive and predictable, so depending on your sound source, it might be an option. It is commonly used in commercial airline cabins to reduce the "drone" of the turbine engines.