Based on my experience, I would say in pure direct mode they do sound the same if used well below their output power limits. Different DACs have different specs but they really are not the bottleneck anyway, not even close.
Incidentally, hometheaterhifi has an article by Dr. Rich on this very topic you raised, and I linked it a few times before elsewhere, but
here it is again for your convenience. I hope you will enjoy the whole article, to save you time, I am quoting the part in the conclusion paragraph. It might have actually answered your question.
"A key takeaway: circuit quality in the direct mode (stereo or 7.1) is almost always invariant to AVR prices in the range of $400 to $2,000. As examples, the $250 Yamaha RX-V367 and Marantz AV8801 ($3000) use the same Renesas LSI chip (R2A15220FP). With the LSI analog chip in these products, the sound of the direct mode is relatively constant, although a more robust power supplies, addition a quality output buffer and enhanced DC blocking capacitor quality can make small differences. "
I believe Dr. Rich is right, not because of the fact that he has a PhD in EE, but because it sounds logical and it is consistent with my own experience. The only part that pissed me off big time is, he compared the Marantz AV8801 to a $250 Yamaha RX-V367. I paid over $3000 for the AV8801 before I read that article. Marantz has since upgraded the HDAM modules that uses more transistors to replace some op amps, but the real bottleneck, the LSI chip Dr. Rich identified still present on the AV8802 and SR7010.