Far from "prevailing wisdom," my 7 channel system evolved from my 2 channel stereo.
I started with 2 speakers driven by 2 monoblocks. Each speaker had its own subwoofer to fill out their low ends.
When I added a screen, I routed the 2 front channel outputs of the HT processor to be one of the inputs to the preamp of my stereo. And I added a center channel and 2 rear speakers driven by three other monoblocks, all sourced directly from my HT processor. These monoblocks are powerful and accurate but do not have the same class of sound as my main front channel monoblocks.
More recently, I added 2 more channels for a 7 channel HT. The 2 added speakers became the rears and the former rears became the surrounds on the sides. My rears are more efficient than the surrounds so I used a lower power stereo amp that I had bought some time ago. Fortunately, it is made by the same designer as my main front channel monoblocks, so at least it does share the same character of sound, although this is of minor importance given the sonic material usually sent to the rears.
Since my main fronts both have subwoofers and all my speakers are close to full range, I don't feel the lack of not having a dedicated subwoofer channel. When I set up my system in my HT processor, I input that there was no subwoofer for the ".1" channel.
