Keeping the signal digital and in the digital domain into a digital power amp where it is converted to analog for your speakers will produce the best possible sound.
Wow, talk about blanket statements.
In any case, there is really no such thing as a "digital power amp" despite the fact that some manufacturers call them that. There are some amps that accept a digital signal that has been manipulated (distorted) to control volume but even then they just move the DAC into the box with the amplifier where they do the D to A and amplify it.