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
In a few months, put that Pangea back on the Yamaha, and hey presto! another cheap - actually, free! - tweak.

Funny acastos! I have tried most of the power cords I own on the Yamaha integrated. Thought the inexpensive Pangea sounded good. In the end, the sound of my speakers became veiled, lacked transparency and a sense of air in the music. I am shocked that the cheap iron lung jellyfish solved all of that. After years of owning audio systems, I learned some things that work are unexpected and there is no accounting for them. Synergy can sometimes surprise you.
Resurrecting an old thread: 

The inexpensive JW Audio Cryo Nova speaker cables I've had for years and tried again have definitely improved the sound of my Klipsch speakers. 
Being an apartment dweller my entire life.. For many years now, if I move, the new place immediately gets new heavy duty (read $5 a pop) AC duplex all around the apartment. Most apartments the duplex are NEVER replaced unless they actually physically fail.SO I suggest same for moving into any new to you dwelling. Most likely new old the place has junk duplex. (though if you move every year??? (I tend to stay put. Previous 17 years, current 11 years and growing...)Geoff's suggestion of cleaning the plugs and duplex anywhere around also good idea (33 posts back) I use the Caig 'Red' cleaner conditioner for stock duplex around the apartment.