OK, so you've just bought
yourself a fancy new DVD player with inbuilt Dolby 5.1-channel decoding. A matching multi-channel amplifier would also be nice but what if your budget won't stretch that far?
For many people, the answer is quite simple - use existing hifi
stereo amplifiers that they either already own or can scrounge for next to nothing. Most of us have progressively upgraded our hifi systems over the years and typically have old - but still working - stereo amplifiers stashed in a cupboard or in the garage.
For example, you can use your main hifi stereo amplifier for
the two front (left and right) channels, plus a second stereo amplifier for the two rear channels. A third stereo amplifier is then used to amplify the centre and subwoofer outputs from the DVD player - see Fig.1.
By the way, you don't need integrated stereo amplifiers with
preamplifier and tone control stages in this application. If you have one or more stereo power amplifiers, they will do the job just fine.