Given this is using a TPA3255 - they could have potentially said it will support 300W of power like Fosi Audio and Aiyima claim on their TPA3255 - and provided different power supplies, but I imagine WiiM are being honest about the max power coming from the shipped device + power supply.
With a larger power supply you get more money from a TPA3255 chipset
e.g. this is Aiyima 'chart' of power supply options for their TPA3255 Amps:
View attachment 3046
So the 60W into 8Ohms probably means they are shipping with a 24V 5A power supply and then updated version might mainly be just a larger power supply, though possible they will be conservative with the power rating to keep the heat down and these Wiim devices have a daughter board with the LinkPlay smarts and keeping that board cool might be a priority.