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
Freezing things in the home freezer. CDs, LPs, Blu Ray, CD players, headphones, cables, power cords, what have you.
Refrigerator magnetic dry erase board... Under the CD player. (on shelf). I have been delighted to have Earl Hines play piano in my living room for several hours today. No on the stereo, in my living room.                
If you have any small crystals.. a baggie of them on the magnetic mat below the transformer in the CD player, and maybe below the main decoding chips.     
$20 for the mat. Crystals ...?               
Hockey pucks.  OK, I don't know that they actually have any impact on sound quality, but due to space limitations, I have to stack some components in my bedroom and it helps give some breathing room between them, hopefully it will help prevent an early death from heat.
These are amazing and highly effective! I use three under all my components. The best value in vibration control, and they look good!

$26.40 for a box of 48!

https://www.supplyhouse.com/DiversiTech-MP-2E-EVA-Anti-Vibration-Pad-2-x-2-x-7-8