First, they are not identical. I said "close to", but definitely not identical. Sorry if I inadvertently stated my point too strongly. I consider it "close to being...." because there is practically just one additional buffer stage in the Marantz preamp and the DDSC HD and AL32 processing in the Denon. The video side is in fact identical (e.g. X4400H vs SR7012),the digital processing, the power supply and the power amp sections also look to be virtually (in case I missed something very minor) identical from what I can see. The 7.1 analog inputs and Denon link make no difference if not used, and I bet 99% users don't use them. The DDSC HD, AL32, like the HDAM were supposedly there to improve on transparency and accuracy, but like the DAC chip thing, the resulting differences may be measurable, but most likely not audible to most humans.
In theory, the HDAM modules, that make up one single circuit board (13 in my AV8801, and of course 15 in the AV8805),does represent a significant difference in the preamp's output buffer stage. That extra stage however, does not make an audible difference to me, nor did they make any measurable and significant difference revealed in available bench tests. If it automatically means better SQ then life would be great and simple. There are many much more older and expensive audiophile class Marantz amps that don't have any versions of HDAM, and Marantz fans still loved them. Why do they implement the HDAMthing then? Who knows, engineers/designers all have their opinions, preference and beliefs that can change over time. Also, I am sure just because they are there, some of the people who know about them will automatically hear a difference while some (like me) may not.
Agreed, but there is a commercial side of the story.. If they stay together long enough though, they might do just that, and then simply change their names to Marnon, or Denrantz etc. Until then, keeping certain exclusive features for each line seems like a good marketing strategy that could help them keep the original customer base of both lines while pushing to expand and sell more overall.
