Write the next sentence in the following story.

How to improve the sound of your stereo system for less than $100
Keep all of your source material clean.
Dirt or oil on your cds or vinyl lps will keep them from sounding their best. Cleaning them regularly costs very little and can make a tremendous difference in the sound quality of your system.
Vinyl can be cleaned with either mild soap and water or a mixture of alcohol and water. Cds are best cleaned using a commercial cd cleaning spray and a lint-free cloth.