Has there been any inexpensive item that enhanced your system's sound?

For me it was an inexpensive power cord that was laying around for years, a Pangea AC9.  I have it connected to my Yamaha A S2000.  I've tried the stock cord on the Yamaha and then some of my other cords, (Wireworld, VH Flavor 4, Acronlink/Oyaide custom cord and a MAC). I've had lots of amps and integrated amps over the years, and this is the first time the Pangea contributed to making better sound. It surprised me because I had tossed it aside and forgot about it.  Power cord performance is such a crap-shoot and dependent on so many other variables in the audio chain.  Any inexpensive item you've come across that enhanced your system's sound? 
Dedicated 20 amp dedicated circuit with a Porter Port. Speaker stands made by Resonant Woods. Large Oriental rug. The rug made the biggest difference followed by the speaker stands and then the outlet. I'm going to see if a new component stand made by Resonant Woods makes a difference but not until 2020. I'm picking up my 2019 purchase on Saturday and I'm done for the year. 
Cheapest was removing the cover from my phono preamp. Opened up the sound almost metaphorically. Refitting the lid closed in the sound. And never play records with a lid on your turntable especially closed. 

Removing all magazines, newspapers and books from the abode, especially telephone books, and relegating them to the trash. I’m not hot doggin’ ya. 🌭
Adding a dedicated 20 amp line just for the music. Everywhere I've lived it's one of the first things I do.