Except it's an extra cable that has to go somewhere different than the first cable. Would turn my living room into a spider's web of cables.
This is the whole trouble now, everything is in the hands of big conglomerates. There is no imagination, innovation or significant progress.
You could easily do this with one cable. To do it you need a standards agreement. You would not want an AC cord coming out of every speaker. That would encourage a boat load of ground loops.
The answer is phantom powering. Since the length of cables to the speakers would likely be large anyway, you would want to have balanced connections.
I would make compact and neat pre/pros. With economy of scale it is obvious these could be made much cheaper than a receiver.
Now I would put half the speaker power supplies in a unit that the pre/pro connects to, this would not have to be a balanced connection.
Now the power supply would have a transformer and put out an agreed DC voltage. This would be high enough to power any amps of power that you would want under domestic condition.
Now the power supply unit converts the signal to balanced if it receives an unbalanced signal. It also puts the +ve DC voltage on pins 2 and 3 and the ground on 1 the ground. The signal goes on pins 2 and 3 as it does now in balanced connections. No DC current flows between pins 2 and 3 as they are at the same DC voltage. This is standard phantom powering practice.
You would have to design a new balanced connector most likely, as the pins of the current connector would not handle the currents involved. This would be an agreed standard.
Now in the speaker you have the regulation side of the power supply, with regulated DC voltages supplied to the various crossover amp stages. This would be cheap to build.
Active crossovers could be built much cheaper than passive ones, as chips, caps and resistors are bought for pennies in quantity, whereas inductors and large passive caps and power resistors are expensive.
The you need class D amps tweaked for the drivers they are supplying.
There you have it. Straightforward and easy to connect, but different from what we are used to. Is it worth the effort? Absolutely!
With the resources of a manufacturer I could have this fleshed out and working in no time. If any want to hire me I'm in.
So you have much cheaper pre pros away from a lot of sources of heat. The major heat generators would be the processor chips.
The power transformer would be in its own unit. That would be best, but you could make pre/pros to output the balanced audio signals and the phantom DC power.
There would be big savings in the crossover. The regulation would just be moved from the receiver to the speaker.
I'm sure the class D amps with economies of scale could be produced very cheaply.
The benefit would be a big improvement is sound quality. Reliability and and longevity would go up through the roof.
With changes in processing technology you would only have to update the pre/pro pretty much.