Music and sound, about the performance and recommendations.

CasualEvolution

I am adding sound to my game and I wonder how much it impact the performance?
I do not want that game behave differently, if the audio is activated or not activated ... even though if it was a small difference.
Now I have programmed that when audio is off, do not play it. But I'm thinking that maybe the way to make sure the gameplay is exactly the same with or without audio, if always play sounds and if are was muted (from options menu) play too but with 0 volume... thus, always would have the same performance.
What is your experience and recommendation?
Thank You!