If you want an accessory, you can always buy the steel puck doorstop that Darko puts on smaller audio devices in his youtube reviews. He's honest about it and says it doesn't do anything to the sound but it keeps the cables from pulling the thing off the shelf. If you decide it doesn't do anything for your WiiM device, you can always use it as a doorstop.
You could put velcro tape on the shelf and the mating piece on the WiiM device, or drill holes in the shelf and use zip ties. Or use C clamps, or spring clamps.
There are all sorts of stupid cables and connectors you can buy, power supplies, spike feet to either increase or decrease mechanical coupling, all of which provide night/day improvements or none at all depending on who/what you choose to believe.
