Dell AX510 speakers pop after having no output after a while

I have the AX510 speakers hooked up to my Dell U2913M via 3.5mm input and power from the monitor itself.

I don't think I had this issue when I first got the setup, but it's been a while since I had this problem. 

After not having to output anything for a bit, when there is sound to be output, the speakers make a popping noise once and outputs the sound. There is also a bit of a delay every time this happens such that I lose about 1-2s of the initial bits of the output.

What can I do? Is there a firmware update??

Thank you.