When I connect a fullhd monitor over display port and a 4k tv over hdmi at
60Hz, then sound is like accelerated on monitor and completely absent on tv.
Using my soundcard, sound it's good.
Hdmi cable is 2.0. Videocard is Radeon 7. I'm using amdgpu kernel module.

Some info about packages:

$ uname -a
Linux debian 5.2.0-2-amd64 #1 SMP Debian 5.2.9-2 (2019-08-21) x86_64 GNU/Linux

$ dpkg -s mesa-vulkan-drivers:amd64
Package: mesa-vulkan-drivers
Status: install ok installed
Priority: optional
Section: libs
Installed-Size: 11750
Maintainer: Debian X Strike Force <debian-x@lists.debian.org>
Architecture: amd64
Multi-Arch: same
Source: mesa
Version: 19.2.0~rc4-1
Provides: vulkan-icd
Depends: libvulkan1, libc6 (>= 2.29), libdrm-amdgpu1 (>= 2.4.97), libdrm2 (>=
2.4.89), libelf1 (>= 0.142), libexpat1 (>= 2.0.1), libgcc1 (>= 1:3.4), libllvm9
(>= 1:9~svn298832-1~), libstdc++6 (>= 5.2), libwayland-client0 (>= 1.15.0),
libx11-xcb1, libxcb-dri3-0 (>= 1.13), libxcb-present0, libxcb-randr0 (>= 1.13),
libxcb-sync1, libxcb1 (>= 1.9.2), libxshmfence1, zlib1g (>= 1:1.1.4)
Description: Mesa Vulkan graphics drivers
 Vulkan is a low-overhead 3D graphics and compute API. This package
 includes Vulkan drivers provided by the Mesa project.
Homepage: https://mesa3d.org/

Feel free to ask for more info. I'm glad to help.