High SINAD receivers don't exist because the manufacturer can't produce them without super high prices or financial loss.
To have high SINAD the whole chain from DAC module - Amplifier module must have high SINAD. Considering the normal AVRs right now have at least 10 channels, which means they need at least a 8-channel-DAC chip and a 2-channel-DAC chip. The high SINAD 8-channel-DAC chip is expensive. For example, the ES9028Pro cost around 15 USD per chip in large supply. Compare to that, the cost-effective ones like AK4458 cost at most 2.5 USD in large supply. That is more than 500%. In addition, you need quality circuit around to retain that high SINAD quality of DAC chip, and it costs more both in R&D and manufacturing. Can the AVR companies tolerate that kind of cost when they are paying exodus amount of money for licensing from HDMI, Dolby, DTS, Room Correction...? I don't think so.
More difficult problem is amplifier. Most audio engineer in AVR company can design decent class AB amplifier module for 8 Ohm load, but achieving the high SINAD amplifier with 4 Ohm load is not trivial task. You either increase the complexity of design or/and raise the amount of output transistor. Both of them is a red for manufacturer as it increase the difficulty in producing, maintaining and cost (heatsink, heat management for 8-10 channel module, not 2 channel in stereo). Buying good OEM class D or licensing them (NAD) for AVR is an option, but cost is much higher than using the not-so-good in-house design.
In the end, money talks