I'll develop my previous post.
Yesterday I got the issue six times. Today three times. I made an interesting discovery, though, that is that you haven't to reboot to make the sound go back to normal: it's sufficient to open the SoundBlaster program in the systray and switch a few times between 2.1 Stereo and 5.1 until magically all comes back normal. On the other hand, it's pretty odd that, apart from the issue, once you select headphones in that same program, next time you switch to stereo you can listen to all the sounds continuing to come from headphones too (and the audio system appears much more stable in this way: perhaps is it so because, while in 2.1 or 5.1, it does not use the OP-AMP that it instead uses while in headphone mode?).
My discovery brings me to think that the problem could reside in software or driver but, on the other hand, makes me despair that Gigabyte will ever provide a concrete and real solution, because on Internet you can find, in a wide arc of time, a lot of reports about Gigabyte's SoundCore 3di-based motherboards affected by the same problem and never - I repeat: never - fixed.
Should I be wrong and should the problem be hardware-related, perhaps with a precise set of producted mainboards, I think that it's not the SoundCore chipset to be blamed though, but the (faulty) OP-AMP on the motherboard. I suspect this because I read also that a couple of guys solved our same problem by replacing the OP-AMP.
Now, a new OP-AMP for this motherboard, on Amazon, costs about 30 € though, at least from my country (Italy). For about the same amount of money, honestly I ordered today a dedicated Asus Xonar, that will be shipped to me on next Wednesday. That should bring an end to this absurd problem, I guess, and anyway more audio quality, to be honest, since with this SoundCore 3di I could listen some high-pitch noise in headphones, when the volume was maxed up (so shielding is not that great too, on our Gaming 7, despite Gigabyte's promises). I simply haven't the time to rule this problem out by multiple and blind tries, because this PC is highly needed for urgent and continuous job (it's built with gaming components because I like to dedicate some spare time to videogames, but that doesn't exclude that the rig is mainly used for work).
For your further reference, today evening I updated my BIOS from F7j to F7r (yes, I was using beta because of the notorious Skylake bug with complex calculations; and I simply upgraded tonight to latest beta). Since then, I had no problem, but I suspect it would be only a matter of time. After experiencing the issue once the very first day I built the system, in fact, I never experienced it in the following three weeks, until yesterday. So time is really random on this problem.
Or could it be that the issue showed again yesterday because only a few minutes earlier my Windows 10 x64 updated itself to latest public stable build? That would confirm that the problem happens at software or driver level, and another confirmation of this would be also that still yesterday, while I was repeatedly having the problem reboot after reboot, I could stop it by reverting to Microsoft drivers and uninstalling the SoundBlaster utility. But, in this way, I lost the possibility to use the microphone from the front-panel of my case (Corsair Carbide 500R)... So, wherever you look at this situation, it's a great mess.
One thing is sure: I spent a lot of money on Gaming 7 instead of buying Gaming 5/6 or Asus Maximus VIII (Hero) because I was convinced by the well-advertised (by Gigabyte) SoundCore 3di chipset. I'm now very disappointed I was substantially forced to buy a dedicated soundcard: sure, thanks to the shipping Asus Xonar I'll solve the problem (at least I hope!) and I'll have a better experience with the sound compartment from now on, but a part of money I spent on Gaming 7 will be obviously trashed. And I don't like trashing money, so, Gigabyte, be sure that you'll never - never - see my wallet again. And I'll advise against you any other people asking me for a good suggestion about hardware. Yes, it's a drop of money in the ocean you're swimming into, so I know you can't care more about this. But revolts start always from tiny gestures.
