I've bought the WiiM Ultra with a pair of Wharfedale Evo 5.2 speakers, have to say I think it sounds great! I did want some floorstanders however the projector screen comes down too far so can't live with them.
Using them with a Pioneer Sub from the old surround system which does seem to add a little, but isn't really required, will upgrade to a larger sub (recommendations welcomed).
Mainly use them to listen to music while reading, and for Movies (but no I do not want to go back to a surround system).