Actually, as Aragain says, toe-ing in to a point IN FRONT of the listening position has the effect of widening the sweet spot. If you'd like a wider sweet spot, this is the best way to achieve it. Of course it will be suboptimal for the listening position but will be pretty good for your friends too.
The tonal balance is preserved due to the dispersion characeristics of most speakers. For a person sitting to the side, the decrease in dB due to one speaker being further away will be offset by the fact that it is pointed more directly at your guest. Likewise with the closer speaker; the increase in dB is set off by it facing further away. As for the prime position, the tonal balance will be as good as if they were slightly toed in, but the imaging will take a performance hit.
The tonal balance is preserved due to the dispersion characeristics of most speakers. For a person sitting to the side, the decrease in dB due to one speaker being further away will be offset by the fact that it is pointed more directly at your guest. Likewise with the closer speaker; the increase in dB is set off by it facing further away. As for the prime position, the tonal balance will be as good as if they were slightly toed in, but the imaging will take a performance hit.