In the world of high-end audio, people like to tweak their systems in order to obtain better sound. This may include buying a number of devices, some of which are expensive, to reach that goal. Audiophiles do things like place pennies on top of their speakers, or demagnetize their CDs, or a number of other things that may or may not make a huge difference in the sound.
Here's a simple tweak that works for everyone, and it will cost you exactly zero money: removing your eyeglasses while you listen to your hi-fi system.
Jonathan Scull first mentioned this many years ago when he was reviewing for Stereophile. The problem with listening to music critically while wearing eyeglasses is that you're putting two very reflective surfaces on your face, just a few inches in front of your ears. Sound waves are going to hit the lenses and disperse into the room, away from your ears.
It's a simple tweak to try for yourself. Just do an A/B comparison during your next listening session. Listen to an entire song with your glasses on, and then listen again with them off. You should hear a giant difference.
Go on, give it a try. Let us know what differences your experience!