Proper voltage and current is easily measurable at an outlet as a start to make sure you are at least playing on a level field. What happens beyond that in regards to power and sound is not practically measurable it would seem. Trial and error is needed, but not blindly. Learn about solutions that solve particular problems, like reducing noise levels with line level gear and optimizing current delivery for power amps, and buy wisely. Lots of "noise" out there when it comes to high end power solutions that muddy the waters. Know the problem you are looking to solve and go from there to end up at a happy place soonest.
I like Pangea power cord products in this regard. They are not overly expensive and each product is clearly designed to solve specific problems as I related above. A very good place to start if one must. Noise levels are often significant with modern gear, especially computer/digital based gear and worth tackling at some point IMHO, but only after the main components in any system are working together well, as an improvement, not as a solution to change the sound in a major way.
I also recommend a decent power conditioner as a must for line level gear (not for current hungry power amps)in most any serious hifi system these days. Furman is a line I like, but even the common Monster strip/conditioner works well.