I don't think I can give this topic justice in a forum format. Give the idea some actual consideration for its potential. If you don't like the idea read another thread!

In the seventies Radio Shack sold some speakers that used PowerLine Carier [PLC] to get the audio signal from the frontend to powered speakers. They did not work well because it predated digital audio and because it was Radio Shack. After that failure, PLC became "hands off" to the audio world.

Add some Analog-to-Digital and Digital-to-Analog converters into the equation and suddenly high fidelity and PLC can coexist.
I have read several articles about video over PLC and, apparently, the noise problems have been solved and there is plenty of bandwidth.
Add channel IDs to the data stream and instantly you can have as many speakers for any channel you want - in any room [yes it does need to be trapped in your own house].

This needs powered speakers with DACs or better;
repackage the M-Block 200 as a Plate Amp [<12"x<9" to fit my M&Ks] and add a DAC. We bolt these onto the backs of our speakers and all we need is a power outlet and 6 inches of speaker cable. Forget stringing cable around the room for those rear speakers.

After R&D, I can't see this technology being real expensive considering you can buy a $40 DVD player that converts digital to analog.
I realize there are other considerations; however, I will not go into those at this point. Suffice this as a bare-bones proposal [I do have a more formal document typed up including diagrams].

Hay, Outlaw, you could be the first to intoduce something that has the potential to turn hifi on its proverbial ear.