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? 
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

- 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


Speaking of cleaning contacts one should clean contacts of ALL wall outlets, even those not audio related. Even contacts of wall outlets in other rooms, refrigerator, TV, computer, air purifier, etc. These oxidized or dirty contacts are a source of micro arcing, the noise of which migrates to the audio circuit.

ptmconsulting, is it not true that many of the makers of audiophile electronics (amplifiers in particular) recommend not utilizing power conditioners and going straight to an outlet?  I have tried quite a few power conditioners (some expensive, like the Synergistic one)  before on sources and on amps and ended up with none anywhere.