I'm starting to think that there is a need for some serious forensic analysis of what is going on inside these AVRs. We have been concentrating on questions from the DAC onwards, and it looks more and more as if there are significant questions to be answered about the digital chain as well. There are clearly some incompetent or careless designs and implementations of DAC and power amplifier stages, but it is starting to look as if manufactures are turning a blind eye to the problems in the digital processing.
By a blind eye, I mean that it appears many are taking off-the-self silicon and software solutions and doing the minimum effort to integrate them into a product. We saw even simple problems with such software cause Emotiva all manner of trouble, and result in poor outcomes. I have a feeling that hardly any vendor is immune. There is clearly a lot of money being made by licensing the various decoders and processors, and a hidden layer of vendors of implementations of these. Nobody ever discusses these components. They are just invisible. You can't even take to the cover off and look at the chips to know what is going on. And yet it is clear that the quality of implementation is B grade at best.
Certifications from the likes of Dolby, THX, DTS are clearly useless, they provide a lowest common denominator, not a guide to quality. Money, and cartel like behaviour on a number of fronts conspire to allow this situation.
On theo forensic front, time to start attaching probes to the I2S feeds and looking at what the heck the DSP is doing to the data before it gets back into the analog world. I'm betting that the answers will not be pretty.