If you want to use your guitar amplifier with your home theater receiver, you will need to use a DI box (direct injection box). A DI box converts the high-impedance signal from your guitar into a low-impedance signal that can be amplified by your home theater receiver. You can then connect the DI box to the AUX input on your home theater receiver.
Here are the steps on how to connect your guitar amplifier to your Yamaha 5240-HTR receiver using a DI box:
1. Connect your guitar to the input of the DI box.
2. Connect the output of the DI box to the AUX input on your home theater receiver.
3. Turn on the DI box and your home theater receiver.
4. Adjust the volume on the DI box and your home theater receiver until you reach the desired level.
You can now play your guitar through your home theater receiver.