Assuming the pure audio you guys have been quoting is pure direct mode,
@nawfal07 is 50% correct
, the fact is, if he uses the RCA output of an external DAC with the Denon's analog input, he could use direct mode, or pure direct mode to bypass the Denon's ADC, DSP, and DAC, but the signal
will not bypass the Denon's volume control IC, so even if the external DAC such as the top Eversolo model, the volume IC will limit it to no better than may be around 104 to 106 dB maximum, likely lower.
Based on Amir's measurements though, even in stereo mode, if DSP is not used, not even bass management, the signal will also bypass the ADC/DSP/DAC. That's made it convenient for him to do his tests/measurements but it is a moot point because stereo without any DSP function is effectively direct mode anyway.
It really doesn't matter because even if you feed the Eversolo directly to a power amp, assuming it has it's own volume control, or a super high quality preamp is used, SINAD will still be bottlenecked by the power amp anyone, there isn't too many power amp that can do SINAD better than 106 dB at any output anyway, only the Benchmark AHB2 and a few Hypex, or Purifi based amps (example: Apollon may have one) can achieve that kind of high SINAD.