List a Condition you know of that will produce Better Sound

For Example:

-Open Baffle always sounds better than a box speaker
-15" diameter Speaker sounds more real than a 6" version
- Heavier Speaker beats a lighter version
- Dual Concentric design beats a separate Mid and tweeter
- Fewer parts in an XO beats more

Okay let the fun begin...

I thought the Armor All tweak resulted in a lot of CDs going bad (CD rot). Sam Tellig tried it, then withdrew the endorsement because of those reports.  Anyone else remember that?
Our garage is opposite the rear wall of the listening room.  I store the 4 'spare' summer/winter wheels for our sports car flat against the wall in the garage about midway up.  The added mass improved the sound considerably.
I've been enjoying the AmourAll treatment since the 80's on hundreds of cd's and it hasen't done anything to any of them....Only make them more musical. Love it! Another tweak that works....Spray your vinyl with distilled water and don't dry it completely. Put it on your turntable and play. Notice a difference in the "smoothness" of the sound.  Almost an "Enhansed" sound. Of course you do. Your dry needle is not laying down on a dry record. Groovy Record cleaner has the same effect if you don't feel comfortable with using distilled water.
I'm with @millercarbon on this one.  Night time audio sounds better than daytime audio.