Because power amplifiers generate heat that must be quickly dissipated, make sure you never block or impede the flow of air through the power amplifier or over the heat sinks. The end result is a more portable and easy to use system with less wiring between components. See the above information to learn about mixers and power amplifiers. More than any other part of your sound system this is a matter of personal choice and individual need. If you use CD's exclusively then that is the only music source you will need to have in your rack sound system.
Microphones convert sound into electrical energy that can be amplified and shaped.
Some microphones have excessive bass response. If, on the other hand, your voice is high in pitch, this is the kind of response that will make you sound the best. Have someone else listen while you test a microphone. Your voice over a microphone sounds completely different to those who listen to you than it does to you. All of the above microphone information also applies to wireless microphones.