Usually, the first time you connect the N90Q to your computer with the USB cable, and turn the headphone ON, it will cause a message to open on your computer, informing you that this new device has been connected, and a software package is being imported. Next time, you may get a warning that your USB device is not recognized by the computer, but that does not mean that the headphone will not work, it just means that you must activate it in the audio control systems. Locate the speaker symbol, which is usually shown at the extreme right in your computer taskbar along the bottom of the screen. Right-click on the speaker symbol. A menu opens, and you must highlight and click on Playback Devices. Now a small window opens, showing the Playback tab, with all available speaker option. One of the options should read something like this: " Speakers. AKG N90 headphones - Firmware version A2.12. Ready." Highlight this option, and then click the "Set Default" button that is now available in the window. Audio should immediately be sent to the N90 headphones as a digital signal, which is then converted and amplified inside the headphones. Now you can enjoy world-class music listening. If the computer will not show N90Q as an option, it is usually a solution to disconnect the headphone, then reconnect it. Sometimes this must be done two or three times before the computer "sees" the headphone.