Play music from laptop over WiFi to existing audio system: how?

@tcatch - That's very interesting. I might buy it. Looking closely at it now. I wish Lightning DS was available for Android. But if I can play music using the music app on my laptop and send it to the Auralic mini, that is what I wanted to do anyway. So, to be sure, I can use my laptop connected to my home network via WiFi and stream music to my DAC through the Auralic mini, right?
Also, I read that the retail price is under $500. So why is this used one $550?

Here's something else I just learned about:
https://hifiberry.us/Those are not much more expensive than a Chromecast Audio and much more flexible. I'm not a big Google fan.
It's amazing to see the price range of the various solutions. From almost nothing to over $2000. The HiFiBerry and the Auralic Mini both interest me.

But I would imagine the audio quality of wifi connection would be inferior to that of USB simply because of the unstable nature of wireless connection.  

Interesting Auralic Mini review here:
https://darko.audio/2016/02/audiophile-grade-streaming-with-the-auralic-aries-mini/

If I was an Apple person, I think the Auralic Mini and the upgraded power supply would be a great choice. But not being able to (not wanting to) use one of its best features, the Lightning DS software, deters me from the Mini just a bit.

Also, am I right that that listing is a bit overpriced? The new price for the Mini is $549 with a 1 year Tidal subscription ($240 value). Without Tidal, the Mini is $399 (outside US). The power supply is $299 (I think). Without Tidal, it seems $550 is a bit high for a used one. Or am I wrong?

One interesting thing is that this shows the hardware I want can be built and it is in the price range I had in mind. Surely some other companies must build hardware like this too, and I'd like to find some of those offerings.
Specifically, a WiFi enabled device that connects via USB to an external DAC.

From another review of the Mini:

Here’s the big question: does it sound better than my DIY Raspberry PI streamers? Hmm, I’d say they are about the same with the PI being a whole lot cheaper. But if you want a ready-made solution, nothing beats the Aries with its great software ...
https://www.musicservertips.com/product-reviews/auralic-aries-mini/

So that gives me yet more reason to think about the HiFiBerry or even something a couple steps up from that. All these Pi solutions will let me run Linux, which is what I like.
If the HiFiBerry sounds about as good as the Auralic Mini like the reviewer says, then it is by far my preferred choice over a Chromecast Audio too.
Interesting thread. Thank you all for the ideas.

But I would imagine the audio quality of wifi connection would be inferior to that of USB simply because of the unstable nature of wireless connection. 

I cannot hear any difference. My WiFi handles up to about 1 Gbps. CD quality PCM audio over TCP/IP requires only 1.4 Mbps I think. I know it's not just bandwidth, but jitter that matters too.

I am using my PulseAudio "free" solution right now and it streams PCM audio over the network. It sounds the same as the USB cable to me. My speakers are Magneplanar 1.7i. My DAC is Onkyo P-3000R. WiFi playback has been flawless all day since I got this working.