To interact with Alexa on the Marantz M-CR612 Melody X, you need to set up the connection between your device and Alexa via a compatible app. Here are the general steps:

1. Download the app: Download the Marantz app or an Alexa-enabled app to your smartphone or tablet.
2. Set up the connection: Follow the instructions in the app to connect your stereo amplifier to the Wi-Fi network and set up the link with Alexa.
3. Activate skills: Activate the Alexa skills for your device in the Alexa app.
4. Using voice commands: Once set up, you can use voice commands to control your stereo amplifier, such as "Alexa, turn on Marantz" or "Alexa, turn volume to 50%".

Be sure to consult the Marantz user manual or online resources for specific, detailed instructions.