Looking for for activation code for 7.1 surround sound for old headphones

Hi - I have been w/o a pc for a few years and only used my work Mac. I have recently built a desktop and I want to use 7.1 surround sound with my Kraken headset I bought 4 years ago or so. I registered the product on my account. How can I get an activation code? I do not have the box from years ago. Thanks Tim