The latest W10 1903 update may cause havoc with your computer's sound card. If it's a Creative card, it will probably not work under 1903 unless the Creative driver etc is updated via a recent Creative update - for me, the Creative update worked on a now older card.
But on my months old laptop, 5.1 AC3 via HDMI to an amp now only plays at 2.0 regardless of how I change the new W10 sound manager settings, even though it worked perfectly well in 5.1 days ago before updating to 1903.
Re W10 1903 - be very wary.