I've been doing testing via the commit listed for the pull request here: Rockchip: add mainline linux support by Kwiboo · Pull Request #3560 · LibreELEC/LibreELEC.tv · GitHub
From what I can tell, when I set the sample rate to fixed and either 44.1 or 48khz, the clicks and pops are a lot better, but are still there. When I up it past that they are VERY apparent.
I tried hooking things up via 3.5mm jack on the device but I don't actually see the output as an option within kodi.
I also tried to pair my bluetooth headset that I usually use with my phone to it, but I couldn't get bluetooth working on this commit version (I swear it works on 9.1.501 as I had paired a PS4 controller at one point)
So, I can't really test outside of HDMI at the moment sadly, but I can confirm the pop issue.