I don't understand what you mean by "streaming from your iPhone to your MBP." If you want high res, load Qobuz on your Mac and connect it to your DAC with USB. This way you can do FLAC with as much resolution as your DAC supports, e.g., 24-bit/192 kHz. AirPlay 2 can do lossless 24-bit/48 kHz, which is good, but you can do better with USB. BTW, mathematically, the 24-bit is more important than increasing the sampling rate, but Apple Lossless may not be ideal.
I started this way too but I found it to be a bit of a pain and I wanted to be able to control the music wirelessly but still stream at high resolution. So I bought an Eversolo A6 but returned it for an Aurender a1000, which sounds much better IMO. These streamers sound great and are just easy.