philips NE5532 single amp can drive speakers : d.i.y 32mW amp

It has 20dB gains: supply 9v . 1ch current is 6mA.
Input power 9v x 6mA = 54mW .　efficiency maybe 60%. then 54 x0.6 ≒ 32mW out.
NE5532 born in 1979 by Signetics Corporation. I use 2002 chip( made in mexico ) .