Missing Activation Code for SurroundSound

Hello, I bought a Razer Kraken V2 Pro a while back and have been using them on my PC for a few years now. When I originally purchased them they were supported in Razer Synapse and I could adjust bass levels, active surround sound, etc. That has no longer been the case for some time now and as I understand it's because Synapse no longer supports headphones with 3.5mm connectivity, and those now "do not need software enchancement". After some digging I found that I could again enjoy the digitally-induced 7.1 surround sound through installing SourroundSound. However, the software asks for an activation code which has been provided with the headphones (I guess), but I've long thrown away the box my Kraken V2 Pro came in. The website mentions that the activation code should be available after I register my Razer product, but I did not receive such. I just checked my Razer account and there are only a Serial and a Product number available there, and none of them work with the 7.1 Surround Sound software activator. Thanks for your input in advance! BR, Ivan