Quality Power Cord

You may also look at used power cables from famous cable companies on 2000s era which sells under $200. They are really good. Next step could be to change their AC plugs with even Furutech Fi-15 (Gold or Rhodium) which sells new ~$100 (both Male and IEC). You will get the same result coming from Power cords priced >$1500! This comes from my own experience. So recently I even tried for a couple of weeks the High Fidelity Ct-1 Power cord ($2800), which was a disappointment based on its price tag and compared to my own Semi-DIy power cables ($300-$400).

You could send me pm and whether you need more info.

cheers,

You can also split the $500 budget for a very good wall socket like the Furutech GTX-D (r) and a Triode Wire Labs 8+ or 7+ or HiDiamond P3. The wall socket upgrade is definitely the first thing to do and should also benefit the other component that is plugged into.  

I strongly agree with the TWL and Hi Diamond recommendations.