There is no such thing as a digital audio amplifier. Class D doesn't mean digital, it's just a description of how the amplifier circuitry is designed.
When CDs were first introduced there were a lot of manufacturers who capitalized on the word digital in the marketing of their amps and speakers but if you look closely at most of the ads, they say digital ready, not just digital. This was particularly prevalent with amps too, because class D amplifier technology was relatively new in the consumer market.
But in answer to your question, it doesn't matter. Most people run class D amps on their sub stage and class A/B on their front stage.