i was thinking about this too with bitperfect. i listen what you are saying. however still not convinced by this argument. need to read more about this. there are some funny discussion on the web in regards to this.
Edit: at the here quoted Audiophilestyle article with measurements. There is CCK mentioned too:
"
- Apple’s Music App, lossless streaming content, USB output with CCK - not bit perfect at 44.1.
- Qobuz, lossless streaming content, USB output with CCK - bit perfect at 44.1 and 192.
"
A discussion about Jitter and bit perfects tests…have to read it myself…. What does a (M-DAC) 'Bit Perfect' test tell you about jitter? | pink fish media