Yes, they use 4562 but very likely lowered rail voltage - nobody sane would risk overvoltage failure in mass production (rail voltage in DAC1 is +/-18V) especially when voltage regulators initial tolerance can make it additional 2x0.5V easily.
They often select very good inexpensive components to keep cost down but there is always room to improvement. It's great that it worked so well for you.
They often select very good inexpensive components to keep cost down but there is always room to improvement. It's great that it worked so well for you.