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I'm using airplay for a whole house Roon solution and I've yet to be worried by quality but that's not for 'critical' listening. I'm starting to lose track of whether 44/16 is really that limited, red book well mastered sounds just fine. I use a Marantz SACD which sounds great but even the red book stuff sounds good on it.
In our house Roon solved the sync problem that airplay 1 had but it was the metadata that got me hooked. It's been great for discovering new music.
I use dsp and volume levelling, switching between Roon output and HQplayer which sounds fantastic but has an 8 second delay. The small difference it makes is only noticeable to me on some pretty high end systems. I would choose the convenience of volume control and volume levelling over the minimal gain you might get without it.
Out of interest what do you need to do over USB that you can’t do over airplay? Is it to connect a hard drive?