Questions about the razer Opus

I am looking to buy the Opus but I just have a few questions regarding the wirred connection. Firstly I have head that the headphones are unusable well charging. I am curious if they are still capable of being used on an auxiliary connection even when dead. Assuming that they can i would also be wondering the power requirements on them though a wired connection. Lastly, I am wondering if you are on a wired connection, are the headphones using the DAC in the headphones or in the device that they are plugged into.