Ion Petroianu, VA3NOI
For sure it is something wrong with your measurement tools.
You cannot put out 24W when your input power is less than 20W.
I suspect your multimeter is not measuring DC current very well. Try the indirect measurement method, using a small resistor in series with the power line and measure the voltage across it. 1 Ohm 5W resistor shall give you decent voltage reading.
I did not measure my current at higher voltage, but a decent estimate is at least 2A.
The PA is a linear amplifier working in AB class. The efficiency of it is 50% at best.