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? 
foster_9
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. 
Carpet/Rug in-front of the speakers placed to catch and absorb floor reflection.  #10 on the Wow Factor.