@Keith1964 - I'll try to explain using an analogy:
Think of a car driving down a major highway. Think about how many various things, designs, and engineering it involves. Now your question on DAC vendors/model is roughly equivalent to which paint vendor they used to paint the barriers. The answer - it doesn't matter as long it stays after x years.
The Same goes for DACs. They are a long time ago made to be good enough to point it doesn't matter.
Selecting AVR I'd be more worried about its amplifier section, which hopefully someone already bench tested and verified its claimed spec. Usually, large AVR companies like D&M, Yamaha, and Sony tend to stay reasonably honest with amp ratings, as long as you read the fine print.