Paul, it's not really stretching it, though. The primary reason people should be concerned with buying a separate power amplifier is if they listen to dynamic music loudly on a regular basis. With certain speakers -- M80s being one of those -- loud passages can take an underpowered amp into clipping and that definitely affects the sound negatively.
D/A converters are a mature technology -- and were even 5 years ago -- so unless they're specifically designed to alter the digital source, they will all be next to impossible to distinguish between in real listening tests.
Many people will claim to hear a difference between high-end amp A and common receiver B until they're asked to prove it in a properly controlled scenario.
