No audible advantage is likely. DACs are a pretty complete science and most push relevant specs beyond audibility already. Expensive doesn't always mean better or higher quality, either. You can generally bypass processing in the avr by using an analog input and no processing by either a dedicated input for that purpose or the "direct" sound mode (i.e. to just use the receiver as just an amp). I wouldn't spend too much on hi-res over cd level, perhaps for remastering or other manipulation, but for just listening to typical audio tracks, again the audibility differences are minimal and it's more about measurement. I'd just keep using the WiiM or other streamers, as long as they're relatively competent.
ps You can even make your own abx tests to see if you can tell differences between cd/higher res with software like Audacity, and some sites have made files available with such as well.