Qobuz also claims on their website that "An analog audio signal is composed of a sine wave" when they probably mean an infinite set of sine waves. They are careless with the truth.
No, Qobuz is correct - analog audio is just a series of sine waves (and cosines). That's the Fourier Theorem. If you doubt that, just look at the squiggles on an LP - a series of sine waves. It's not infinite, though. To do that you'd need infinite bandwidth, which isn't needed and isn't possible.
Streaming is different from downloading, which can be bit-perfect using TCP/IP. The functional difference is that you can start playback of a stream before it is complete. Nothing in the world can guarantee the future will be error free.
But the future is "error free" because Qobuz is using TCP/IP and the file is at least partly cached before playback begins. And even hi-res audio requires a download speed of only around 10Mbps, so there's plenty of time for any damaged packet to be re-sent.
TCP/IP only guarantees bit perfect transmission after the transmission is complete ...
It isn't clear what you mean here. TCP/IP guarantees perfect transmission with the transmission of each packet. Each packet is "complete" unto itself.
Qobuz is very tight-lipped about the actual protocols used ...
My experience is just the opposite - I've found Qobuz to be remarkably accessible and transparent about its protocols. My information regarding how Qobuz works comes right from its US execs David Solomon and Dan Mackta.
My only connection with Qobuz is as a paid subscriber and to be clear, I have issues with the service. In particular, its files are often the "remastered" compressed versions, so my local files often sound better. But facts are facts, and Qobuz delivers bit-perfect audio direct to your streamer, provided your connection speed and network are capable to the task. And for audio, those requirements are minimal - almost trivial here in the third millenium.