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
Foster_9...  I agree Porter Ports are very good...had them for all the outlets that service my system....but I changed to Maestro which was an immediate improvement. 
stringreen, go figure.  After like 4 or 5 years using a Maestro, I decided to try a Porter Port. 
Essence of Music 2 step CD treatment which is actually kind of expensive but averaged out the cost per CD is quite low.
I epoxied a little brass plate/shim to my Denon DL103 MC Cartridge

The fastening nuts now tighten down on the brass plate and not the plastic body

Take a look at My System for a photo

Improvements...
- far more clarity
- deeper bass with better control and precision
-  improved 3D imaging.
- much faster dynamics

I also applied the same technique to my Soundsmith modified version of the Denon DL103 with even better, more noticeable results

Definitely the best $12 I've ever spent in this hobby

:-)
The following are free, and are probably the most important things you can ever do.

- check the set-up of your speakers, and correct it if they are off even by a little bit

- try putting some natural room treatments at the obvious spots and see if it helps with either diffusion or absorption

- clean your contacts, all of them

These others are relatively cheap.

- have an alcoholic beverage of your choice, in moderation

- do something to improve the power delivery to your components, be it a conditioner or replacing stock power cords

Enjoy