Your friend is right because garbage in results in garbage out. The best solution is a separate ring mains from the junction box followed by a good multiplug a la Acoustic Revive Rtp-4 and good mains cables a la Acoustic Revive Power Reference or upper range Nordost. I suggest you also punk down for some good fuses: Furutech as well as Hifi-tuning work wonders. If you want to go further you can apply WA power chips or various forms of ground reinforcement such as Acoustic Revive Rgc-24 and/or Audioquest Ground Control.
In my experience cleaning up the power yields bigger benefits than buying new equipment
In my experience cleaning up the power yields bigger benefits than buying new equipment