Why is the Voltage Gain 54 dB instead of 50 as stated in the problem?
could be a typo... quick analysis....


Voltage gain, Av remains ~50dB or 49.7 @16Ω assumes Av=no load


(negligible load loss -0.3dB @16Ω)  

Current gain, Ai=Av*Rin/Rout or in log format Av(dB)+Ar(dB) 


where  Rin/Rout= 1M/{1kΩ:16Ω}  = {1000:62,500} = {60dB:96dB}

Power gain,   Ap(dB)=Ai(dB) + Av(dB) = {50+60;49.7+96} for {1kΩ:16Ω}