To reduce EMI noise and switching power losses at 50:50 duty cycle, when using AD mode, use two step SMPS output voltage control. Set-up two different SMPS output voltages, just like class-G topology.
For example : set-up SMPS output x volt and Y volt (X volts > Y volts). Y volt support low wattage case and X volt support high wattage output power. The SMPS needs feed back circuit to support this function.
The reduction in voltage at no/low output levels results in lower switching (idle) losses, resulting is lower power dissipation. It also reduces the amount of overshoot on the switching edges, which is a primary contributing factor to EMI generation.