I just purchased this device today and discovered that this horrible bug is still present. This is *completely* unacceptable, Corsair, and I will not be purchasing anything else from you in the future!
Although Corsair hasn't fixed this problem (that they've apparently known about for nearly a year!), there is a workaround: The "Equalizer APO" program can boost the mic input to acceptable levels. I had the program installed to address an audio issue with some other headphones that were really, really loud by default and decided to try the program with these Corsair headphones as a last step before packing them up to be returned for a refund. Boosting the mic gain by 10 dB seems to have put the audio gain into an acceptable range. It's extremely disappointing and frustrating that I had to try this in the first place but this solution/workaround may work for others. I imagine that other programs that do similar things may work, too.
