A singer is only as good as the equipment they use.
You can be the best singer in the world but if you sing through an inadequate P.A system, no matter how good a singer you are your sound will not be good.
The same rule applies to being able to use the equipment to it's best.
In other words you can have a great voice and top of the range sound system but if you don't know how to set a good sound it will still sound terrible.
Read more in my article http://www.thesingingtutor.com/equipment.htm