asahitoro - Well, the WiiM Ultra is a complete solution and people with many systems are happy to use it for streaming with its integrated DAC. Some also go with an external DAC.
A WiiM Pro/Plus with an external battery-powered 5v solution will sound better than the Ultra with a good system and fairly good external DAC. The external 5v power is a great option for those WiiM devices. (The WiiM Ultra does not have this option.)
This is somewhat system dependent. For many, the WiiM Ultra as both streamer and DAC will be an easy win.

