It's a 2 part process. During encoding they attempt to remove any effects from the ADC but after this it's expected that the MQA decoding process takes into account the DAC and attempts to compensate for it. It's most certainly NOT generic. The DAC must be measured, corrected and submitted to Meridian for certification.
Meridian _do_ have a generic ADC compensator however, for encoding previously recorded high resolution sources when the correct filters are not known. I think that's maybe what you were thinking of.