Output Sound as Input Sound without a microphone!

1. Open up Master Volume's window by double click on volume icon in taskbar.

2. Choose Options>Properties which will open up Properties' window.

3. In Mixer device list, choose your input device. E.g " Realtek HD Audio Input". Then click OK.

4. Tick the checkbox in Stereo Mix's column to use it. Adjust the volume as desire. :)

OR

1. Go to Control Panel>Sounds And Audio Devices and navigate to Audio's tab.

2. Click on Volume's button in Sound Recording's section. And repeat step 4 like above.