Currently i need to design a circuit that can modify the audio amplifier to consume less power.

In here I have a doubt is regrading why the Output of the audio power is high will effect the power consuming become very high too? Since the audio power amplifier convert the low input power become high power output?

 

Currently i need to design a circuit that can modify the audio amplifier to consume less power.

That says that you have an existing design to work with, i.e. "the" audio amp. Perhaps you could post the schematic?

 

If your audio amplifier circuit is a class-AB linear circuit then its uses a small amout of current when it is idling. At full power, about 60 percent of the power supply power goes to the speaker and about 40 percent of the power makes heat. At 2/3rds power then half the supply power goes to the speaker and half the power makes heat.

If you use a class-D switching amplifier circuit then its idle current is the same as a class-AB linear amplifier but at full power the power wasted that makes heat is only 10 percent to 15 percent.

It is nearly impossible to "modify" a class-AB amplifier into a class-D amplifier.
If you want your amplifier to consume less power then simply turn down the volume control.

If your amplifier is class-A then it wastes a lot of power making heat all the time even when it is idling. It is nearly impossible to "modify" it so it consumes less power.

 

if i want to design less power consuming and didn't reduce the sound. which mean when i double the power, the loudness also can double? is that possible to make it?

 

When you double the output power then the power taken from the power supply also doubles if it is much more than the idle power.

When the output power is doubled then the loudness is not doubled because the sensistivity of our hearing is logarithmic (so we can hear very low level sounds and hear very loud sounds), not linear. Double the output power is an increase of only 3dB which is only a little louder. 10 times the power sounds twice as loud.