HDMI-ARC noise issue

Hi everyone,

I recently bought a WIIM Ultra. I am generally satisfied..
I have only one problem;
If I connect my TV output via toslink, the overall sound quality is acceptable and there is no noise, but the volume cannot be controlled with the TV remote. You definitely need to use the Wiim remote or your phone..
If I connect my TV via HDMI-ARC, I can control the volume with the TV remote, but there is a serious noise problem. Even if I put my ears to the speakers when the HDMI input is not plugged in, I cannot hear any meaningful noise. However, when I plug the HDMI cable, there is a distinct "hiss" with all inputs.
As a solution, I thought of using an HDMI-toslink converter. However, I am not sure if the TV remote will work in this case. Or that the sound quality will be at the same level as HDMI.
If you can help me in this sense, I would be very happy.
Thanks in advance.