You think the HDAM of Marantz will actually result in worse measured performance compared to equivalent Denon models? I was actually wondering if the Marantz versions would measure better because of the HDAM(not because I'm aware of any specific technical advantage, but because Marantz markets HDAM as a feature that offer superior fidelity)
I always wonder if the HDAMs would not increase distortions, because it is an unity gain buffer stage placed right at the end of the preamp signal chain. So logically, anything that contributed to distortions would still be there and the HDAM will undoubtedly add its own distortions, however tiny, resulting in a theoretically possible and likely higher distortions, all else being equal.
The I read Dr. Rich's comment in the hometheaterhifi.com's review and he seemed to be alluding to the same idea. If you are busy, just read the paragraph before the conclusions, where he wrote:
https://hometheaterhifi.com/reviews/receiver-processor/processors/marantz-av8805-processor-review/
"Harmonic distortion has not improved from the AV8802 to the AV8805 as was expected from the new chips. The change in the worst-case THD specification between the chips used in the AV8802 and AV8805 points to a 50% distortion reduction. We know the distortion is not from the AKM AK4490 DAC since the THD increased as we changed the output level from 2VRMS to 4VRMS with the volume control.
It is possible the HDAM discrete circuits past the new analog ICs are the dominant distortion source. The only way to find out is to open up the case and start probing internal boards which is not something we do here at Secrets."
Now if you remove those unity gain HDAM buffer amps and the balanced I/Os, the 8805's signal chain would be virtually identical to the 8500 and even the 3600's, at least in block diagram form. Obviously the 3600 has the lower grade AK4458 DAC chip too. The other major difference is the DAC filter selection. Marantz chose the slow roll off filter, causing their models FR to drop off early and lost >2 dB at 20 kHz.