Wireless vs. USB

Before dropping major $$ improving in my digital front end, I'd like to hear from more knowledgeable users on this question: Why does a wireless signal, when received by and transmitted from digital player to DAC via good USB connector, sound better than pure wireless received by an all-in-one streamer with DAC -- even though both use the same DAC? Some Aurender digital players output ONLY high-grade USB (no optical, coax, AES/EBU) to DAC, whereas others like Cambridge 851N are all-in-one streamer/DACs (with digital preamp capability too).The Cambridge, of course, receives USB in (among others) and outputs line stage.

If this simply reflects the principle of specialized function -- one operation per device, no clutter like that found in line stage preamps with onboard phono and DAC -- then I get it. But since even USB from laptop to streamer/DAC sounds better than wireless signal direct to streamer/DAC, maybe the answer is something simpler than just higher quality, single-function components. After all, my Macbook Pro is no Aurender digital player, yet its USB out to Cambridge still sounds better than streaming Cambridge alone.

Advance thanks for advice. Still fumbling my way around in this brave new-ish digital audio world.