I have started using iphone (13) as a streamer a long while ago before purchasing Ifi ZS as a dedicated streamer. When playing music through an iphone and an external DAC, its SQ is better than the following different setups:
iphone > window laptop/Mac Air > iphone w/ Apple dongle > iphone internal DAC
When compared with the Ifi ZS, I am pleased to report that, through the same external DAC, the iPhone sounds almost on par with the Ifi in my system (Buchardt S400 ii / Parasound amp / Schiit DAC). The Ifi ZS has a bit more body in mids but iphone is no slouch. The bass is as weighty (try China Hok-Man Yim: ’Poems of Thunder’ eg), high ends/mids are as neutral, soundstage is as wide, and the noise floor is dark as well. When streaming from Qobuz in particular, the app works much better than a UPnP application like MConnect for Ifi.
I continue to use the Ifi ZS simply because I prefer playing music from an SSD / HDD. I collect hi-res files and don’t stream as much.