Regarding power conditioners, my Puritan PSM156 was the single most beneficial addition to my full system (other than swapping out speakers).
I suspect that the choice of power conditioners might be somewhat dependent on the types of issues you have, so it's difficult to predict which conditioner will address things that your system might be susceptible to and the things that are prevalent on your AC at home.
One thing I learned the hard way is to first check that the outlets are grounded and wired with the correct polarity. It's surprisingly common for home electricity to be wired incorrectly in some essential manner.