When you say USB host mode to PC, are you using the rear Micro USB port or the full sized USB port on the left side of the X7? I didn't know the host-mode USB COULD connect to the PC!
Are you using the X7 on a desk? How often do you have to rebalance chat/game? I've been happy every time but once just using the default game/chat balance, the one time I wasn't was when a friend had his mic further away... I highly recommend trying a USB mic if one shows up on Massdrop or something. The more I use the X7, the more I forget about the mic... I just think of the X7 as mostly a source component with a nice amp and DSP. Which is why I was surprised last night when my GF called during a gaming session and the X7 switched to the call. Nice not to have to take off my headphones to pay attention to her (and I didn't stop playing, either XD ), not once did she mention the mic quality or anything about the call being different. So, that's cool I guess.
That lack of hiss and noise is what the 127 dB DAC (and clean, discrete, isolated amp) is all about, premium components are so clean that, with no music or game playing, you won't hear the difference between the amp being off or on besides the lights and click from inside the amp (a relay). With a lower noise floor, it seems like subtle nuances come forward in the audio. When you compare the X7 to the Z, your motherboard, or your mixamp, listen to a well-recorded live song... You may be able to sense the size of the room from how the performance bounces around off the walls. It's pretty cool!
Creative support and I have been communicating about the E1, we've come to the possibility that it might be a lemon. Possibly the first one with my particular issue (though everyone must press firmly till analog interconnect cables "click" into place, which is odd next to the more "normal" USB connection). We're going to exchange it.
Tomorrow starts my 2-day weekend, hopefully I'll start my YouTube playlist on different DSP headphone units, and hopefully get a lot of views