Hans Beekhuyzen on his YouTube channel has answered this question time and time again. The answer is that a better streamer will sound better to a higher end DAC compared to a lower end streamer into that same DAC in a revealing system.
He has tested the WiiM Pro Plus in his three "reference" systems at various price points and can tell a good sonic difference even in his lowest end system.
This doesn't mean the WiiM Pro Plus is "bad". For its sub-$300 price point it is amazing what you can get, but no it isn't a "giant killer", even acting as a streamer only.
Help settle a streaming argument!
This is a SQ argument and is as follows- I argue if you connect your streamer to an outboard DAC the streamer does not matter it’s just serving the music to the outboard DAC to do the work. Therefore, buy a basic streamer. The other is that you need to buy a top quality streamer and DAC to get great SQ.
I liken it to cd players or the more pretentious cd transport argument- if the intent is to connect to outboard DAC the cd player doesn’t matter the outboard DAC DOES!
features and functionality aside! Thoughts…..