2 audio module isolation

Hello all
I'm working on FM radio plus bluetooth receiver project.
When there is no bluetooth device connected i want to use FM module, othwrwise switching off FM radio and play music from bluetooth.
Both modules I want to connect to 2x3W aplifier.
My question is do I have to somehow isolate FM radio audio out
lines from bluetooth audio out lines since they will be connected to the same audio in lines on amplifier? If yes how to do that? know I can use 6 relay switches but maybe there is some simpler way?

Thanks in advance for any help

6 relays?

Ground can usually be common to all units. So that is a permanent connection. You only have 2 sources so a relay with NO and NC contacts can be used. The output to the amplifier uses the center contact. Then you know the L+R stereo signals must switch at the same time so a relay with 2 sets of contacts can be used.

Texas Instruments, for example, has a range of analog switches which could be used to replace a relay in certain applications.
Some of the example circuits here show the devices in the audio signal path. I'm not sure a HiFi enthusiast would approve, though, and some of the packages may not be ideal for hobbyists.