Thank you very much for your time, this is what I was looking for in terms of DAC chips info.
Even though the DAC chip itself may have a small contribution to the sound, around 10% from what I hear, is is important to have a very good HW base to be able to implement on.
NAD definitely use "innovative marketing" to boost their prices up, it's a reality.
Difference from "better implementation" is, in my opinion and experience, overrated. One example I can give you is my experience with Oppo's BDP players that used top ESS DACs. I bought in to their marketing hype on their implementation approach, when they first introduced the Oppo 95. That thing used a separate 8 channel ESS Sabre flag ship DAC ES9018 (old now but still have better specs that any AVR/AVP's) of today's for two channel stereo playback.
It used all 8 channels for just two channel stereo (4 DAC output per channel), below was the marketing bs at the time, quoted from Absolute Sound:
Oppo BDP-95 Blu-ray/Universal Player (TPV 103) -
www.theabsolutesound.com
"
Dedicated stereo analog output: The BDP-95 offers a dedicated stereo analog output with “specially optimized ES9018 DAC and output driving stages.” Oppo adds that, “each output is driven by 4 DAC channels stacking together to achieve even higher performance.” The stereo output offers two sets of output connectors with different associated drive circuitry. One set provides XLR balanced connectors while the other provides RCA single-ended connectors.
Oppo emphasizes, “the balanced output features a true differential signal path all the way from the DAC to the 3-pin XLR connector.” There are even setup options for running normal or inverted XLR pin-out polarity configurations. Frankly, these are the sorts of features you might expect to see in multi-thousand-dollar audio-only players, but that are more-or-less unheard of in universal players selling for under $1000. "
So the specs of the 95 were considered excellent in those days, much better than my Denon DVD3910 that I paid much more for, than what I paid for the Oppo. Did it sound better? No, not to me anyway. The Denon used a higher mid range PCM1796 (much better than the 1791) that has specs far below that of the Opp's ES9018, and implementation was nothing special, not stacked, no differential connections, but it sounded just as good.
Within a couple years, I traded the 95 in for the BDP-105. By that time Oppo has given up the stacked approach so it only need half of the DAC channels, but it managed to measure better than the 95 in THD+N iirc.
Better implementation will get you better SNR, THD, all else being equal, but the difference won't be audible to humans.
So probably I'll see a bigger difference in sound, upgrading the speakers and get a more up to date device, ex. the NAD 778
I dare say you will definitely hear a bigger difference, by upgrading he speaker, and get a more up to date device, but NAD would not be a good choice because you will pay more for less, less in terms of lower measurable performance. However, if you believe in the benefits of using Dirac Live, then it could be your best choice. I played with the trial two channel version, like the interface, but did not find it any better than Audyssey in the range below the room transition frequency based on plotted graphs and my subjective listening comparison.
