The most cost effective AC power enhancement you can make for your system its to have a licensed and bonded electrician install a dedicated line to your stereo system. Ask him to install it on the least noisy phase (for example the one that your refrigerator is not on). Ideally 10AWG Romex with a 20A breaker. Otherwise 12AWG Romex with a 15A breaker.
The second most cost effective AC power enhancement is to have a proper grounding system installed on your main panel (at least one 6 foot copper rod driven into the ground; get an array of three, start grounded for better performance).
In Tempe, we work with an electrician that I’ve briefed on the best techniques.