A seperate DAC will be better than any DAC built into an amplifier or CDP because they can focus all their engineering efforts on optimizing the DAC's performance without being constrained by the design considerations of an amplifier or CD player.
But an argument should be made for the synergy of audio components, where their designs are optimized for the entire audio path. In this context, having a DAC integrated into an amplifier could potentially lead to a better and more satisfying audio experience.
The integrated design allows for holistic optimizations, ensuring that the DAC, amplifier, and other components work together seamlessly, enhancing overall audio performance. This synergy enables manufacturers to fine-tune the interaction between different elements, potentially delivering a more cohesive and pleasing sound quality for the end user.
So which is better? I don't know, sorry.