@jjss49 my understanding is that it is a hardware implementation in the 590 from late 2020. They came out with a new version that had power standby as well as MQA on all inputs:
Direct quote from a Hegel employee on the hegel Facebook page:
“MQA is a hardware feature, so this has nothing to do with firmware upgrades. H590 with standby has the same DAC implementation as H390 with MQA on all inputs.”