Welcome to the forum. The search tool is your friend, especially for a topic that has been written about time and again.
Yes, your entire audio system (as well as the phone, nav system, and voice control, if you have those) is fiber optic.
2005 S500 4-Matic
with Gateway 500 iPod integration
1978 450SL restoration project
Formerly: 2000 S500
with Ice>Link iPod integration
Moto V710 phone with MikBox
Upgraded Voice Control