Bwahahahahahahahaha! Too funny, Dave.
The world that lies beyond your experience continues to elude you...
The engineers at many companies like dCS would just shake their heads and smile.
Let's say you have two computers, a laptop and a desktop. When you copy a file -- say, a WAV or FLAC audio file of your favourite tune -- from your laptop to your desktop via your home network, what effect do you think the power supply, network card, or audio DAC in the laptop will have on the sound quality you hear when you play the audio file on your desktop?
The answer is that as long as the file has successfully copied, the laptop's power supply, network interface, and DAC (in the sound card) have no effect on the sound at all, because the conversion to audio is done
entirely by the desktop machine.
The copying process (performed by the operating systems and network hardware) ensures that the file copied to the desktop machine is bit-for-bit identical to the file on the laptop, so no matter how that data gets to the desktop machine -- whether copied over the network quickly, or slowly, or even laboriously typed in via the keyboard -- as long as it's the same data on the same desktop machine, it will sound the same on the desktop machine.
It doesn't matter what the laptop's power supply, network interface, or DAC (in the sound card) are doing; as long as they're working to design specifications (and sometimes, even if they're not), the source file on the laptop becomes an identical bit-for-bit copy on the desktop. The power supply, network interface, and DAC in the laptop have no effect on what's played by the desktop. In fact, once the file is copied, you can turn the laptop off!
Only the audio DAC (perhaps in the sound card, perhaps external) in the desktop will have an effect on the sound, and the power supply in the desktop machine might have an audible effect on the DAC's conversion of digital data to audio.
The OP's scenario is exactly the same. The audio file on the sender computer (Mac, MacBook, iPhone) is copied to the receiver computer (Apple TV), and the receiver plays it. As above, the power supply, DAC, and network interface in the sender (Mac, MacBook, iPhone) have no impact on the sound quality of the data played by the Apple TV.
The only difference between the OP's scenario and my example above is that the receiver starts playing the data
while it's still being copied. As above, the file is copied from the sender to the receiver and the receiver stores it in memory and/or a file called a
buffer, but the receiver starts playing the data from the beginning of the buffer whilst it's still being filled at the end.
However, because the receiver starts playing data from the buffer
while it's still being sent by the sender, it's possible for the network to be slow enough -- usually due to network problems -- that it plays all the data in the buffer before it reaches the end of the song. The problem is that the buffer is being emptied by playing faster than it is being filled by copying from the sender.
Rather than annoyingly pause playing to let the buffer fill again, many audio systems recognise when the buffer is almost empty and likely to become completely empty. When that happens, the receiver sends an instruction to the sender to send less data, so that filling the buffer will (hopefully) become faster than the buffer is emptied by playing.
Unfortunately, less data doesn't sound as good as more data. The result is degraded sound due to network problems, but the sender's power supply, network interface (if it's working enough to not cause network problems), and audio DAC have no effect on the sound quality at all.
