The reason most people add a power amplifier to a receiver is to get more total audio power.
Many receivers don't have a big enough power supply, and the power available for each channel may drop down to 40 watts or so when all channels are driven.
By adding a stereo power amplifier to drive the front channels, the receiver has two less channels to drive and can do a better job with the rest.
Of course, you can't do this unless your receiver has preamp outputs for the front 2 channels, which many do not have.
There is very little source material that has been properly recorded or mixed for more than 5 channels, so the value of anything beyond 5 channels is a debatable issue.
It is also worth considering whether to spend money on more than 5 channels or whether to spend the same amount of money buying better speakers for the most important 5 channels.
Originally Posted by joejack11
I'm curious about an idea i had, I'm sure it was probably posted before.
Lets say you got a 7.1 receiver, and it was Pre amp outputs, can you pair that with an Amp, says say Front left & right, so now the amp, you add 2 speakers to it,
making it so theres 9 channels of sound from 9 speakers?
or is my idea busted?