I just looked at the WiiM Mini, that's pretty cool. My first foray into streaming was was with an Apple Airport Express 2 (802.11n Wi-Fi Base Station 2nd Gen A1392) that performed the same function. They were discontinued in 2018 but still available on ebay for around $50. I believe it came with a 3.5mm to 2-Male RCA Adapter to plug into the pre-amp.
I was a little late to streaming. I originally did it so my daughter who was 15 at the time could stream her music from her iPhone. According to her, I only listened to music by dead people. She was wrong of course, they were only mostly dead.