I would refer to Shunyata… the founder has a good video on the subject. The point is that power is like a lake not a hose. The reality of us that have experience is that a high end power cords are the most effective at improving sound… the second is to replace low quality Romex with a 10 gauge direct line or better. Depending on your power grid, a power conditioner can be at the beginning or end of the list.
One thing to notice is that great sounding audio equipment invariably has a large amount of technology and weight dedicated to power… it is the foundation of high quality sound.