Historically, it was said that a separate transport / DAC would generally give better sound than a standalone CDP. Separated components, two power supplies etc.
Nowadays, it seems a DAC is used if you want streaming, not for redbook playback only. Besides that, I question why Chord Q-test uses a wall-wort (is it even regulated?) That's the best they can do with a $1,995 DAC? When Musical Fidelity prices goes from M3 $1,599 to M6 $2,889 largely due to a better power supply. Some thinks it makes a difference, some thinks it doesn't.
The other question is: is CDP better because the transport and DAC are designed as one to be used together? Does mixing and matching transport and DAC deteriorate sound due to some incompatibility issues?