Upgrade with best price/performance ratio


Just wondering what was your upgrade with the best price/performance ration in your audio journey ... like upgrading an IC, preamp etc ...

Let me start:

-Corian pieces leftover from kitchen upgrade project

out of boredom I used the Corian chopping boards and put them in between the shelf's MDF board and BDR cones. The effect was a big surprise ...

- much quieter background, solid bass and cleaned up mid and treble.
kschiu
by far the best price to performance ratio, cleaning all your contacts with pro gold, jewelers polishing cloth and pipe cleaners is all you need, it makes a huge difference, funny how I know so many audiophiles that will spend thousands to get maybe a different sound, but wont spent less than twenty, for BETTER sound.
Mint LP protractor
Scotch Foam Tape between cone footers and tile floor
Two granite slabs on tops of sub woofers
Furutech receptacles
Thats easy , dressing cables , costs pennies , cleans up the sound . Down fall is that in an elaborate system it can take days .
The new and improved BOSE 901 series 6 MK2's have the best price/performance ratio that I have ever seen in all the years I have been in this hobby!..