The TDA7492P, a mini hifi amplifier with Bluetooth and line in does not allow line in, it jumps to Bluetooth soon after the start and blocks the line in signal.
It goes like this:
How can I disable bluetooth temporarily for line in to work?
How can I disable bluetooth temporarily for line in to work?
It appears that you can't. Also this amp has no line in.
Googling for 'tda7492p bluetooth amplifier board manual' shows that the 3.5 mm jack is a headphone output rather than a line in.
Picture from manual on product page
Apparently signals injected into the headphone jack will feed through to the power amp until the Bluetooth-sourced signal starts but it doesn't seem to be the intended operation.
If you need an amp module with line in I suggest you buy one. Note that a constant refrain on this site is that you should only buy products which are adequately documented for your purposes.
You might be able get a Bluetooth transmitter for your line signal. You'll need one that doesn't require a user interface on the receiving device to set it up.
