I think it seems credible. No way any manufacture will change from a cheap 8-channel-DAC Ak4458 to something like ES9018, which is more expensive and require new R&D in such short time for low price products. And there is also a shortage of ESS chips right now.
PCM5012 is decently good, cheap & plenty as Texas Instrument has much better production capability than ESS. Denon also has experiences with PCM5102 for a long time. So as a big manufacture like Denon, PCM5102 is much safer & sensible choice, especially for bread-and-butter products ( 4700 or 6700 AVR). For the more expensive products, they can use better DACs like ES9018 & their remaining AK4490.
First of all, I don't remember the ES9018 being mentioned by anyone and, understandably so as the cost for those would be prohibitive for use in any AVP/C/AVRs. So it is easy to agree with you that there is no way any manufacturer would do such a switch from a mid range IC to a top reference class one.
Other than that, I understand your point about the 5102 as a possibility though for reasons I cited I still think it would be very unlikely. Also, if it is credible, then how come there has been no posted links to the source of information directly from Denon?
On the other hand, we do have info from Denon on their Japan website and that's why I don't think the claim of the PCM5102 is credible, again, unless someone post links to info from Denon or Marantz.
I hope you don't mind reading the following as I would like to know if you see what I see, that while the board definitely looks different than the one for the AK4458s but there appears to be still two 48 pin DAC ICs on board; and there's no sign of 7 to 8 PCM5102 (for the main zone) plus two more PCM5100/or 5101 (for the secondary zones):
(8) Denon Replaces AKM AK4458 DAC IC in X4700H and X6700H | Page 6 | Audio Science Review (ASR) Forum
If you magnify the photo of the DAC board you can see the 2 DAC ICs that seem to have the same pin layout, or as least the same pin numbers as the AK4458. It is not possible to tell the model/part numbers, other than we already know it is a replacement of the AK4458. I assume there are other DAC ICs that also have 48 pins, at least the ES9006 would be one of them.
So based on pin numbers that can be seen on the DAC board posted on Denon.jp, I do not think it is likely to be the PCM5102. I hope it would be one that AKM is still producing or have a lot of inventory, and is comparable to the AK4458 in specs. If not, then I guess the next best would be the ES9006 that is only 4 dB lower in SINAD than the AK4458.
As an aside, the following video (thanks to bigguyca) on the SR8015 that has the AK4490 replacement DAC:
Denon Replaces AKM AK4458 DAC IC in X4700H and X6700H | Page 7 | Audio Science Review (ASR) Forum
If you fast forward to the 26 minute point you will see that Marantz has used the ES9010K2M. That is downgrade, in terms of the SINAD spec (6 dB lower), from the AK4490. So since D+M has already used the ESS DAC ICs in their higher models, it is not inconceivable that they may use the ES9006 on the lower models such as the AV7706, SR7015 and SR6015.
Regarding the ES9018, that's a reference class DAC IC that I highly doubt you would find any of them in AVP/C and AVRs regardless of price. The highest ESS DAC ICs used in flagship class AVP/C/AVRs seemed to be the ES9026Pro that is more comparable to the AK4490 but not quite at the level of the ES9018/9028/9038 or even the old 9008.
Unfortunately we are all guessing, until we see some evidence. Good thing I am good for at least a few more years (hopefully) before I have to face another update/upgrade decision.
