We still use an Airport Express with a Nordost Heimdall iKable Mini-DIN interconnect to the 552. It sounds great. This solution is most of what my wife listens to for Pandora and Spotify.
The WXC-50 does look good. I see a lot of detailed negative reviews on Amazon, which gives me pause, but perhaps they’re for more demanding situations than mine.
USB plug from iPhone to AQ Red and 3.5 to 2 RCA phono into amp a decent dac wired to your amp will be your best bet as connecting an iPhone to anything using its own internal dac will not sound good even for casual listening.
I bought one for my daughter a few years ago, and was surprised at how well it performed. In particular, setting it up with WiFi from a basic ISP supplied router, it just worked reliably every day. I then bought two little Yamaha wireless speakers for other rooms, and in quite a large house, they worked flawlessly, day in, day out, even with all 3 units in multiroom mode, from the same cheap nasty router which she shoved under a table in the hall on top of a pile of cables. Try doing that with the Naim equivalents, such as a 272 and two Muso QBs at ten times the price, and I would predict that you’d have a connectivity nightmare on your hands (albeit with hugely better sound quality when it did work) but perhaps we were just lucky.