My Yamaha AVR basically does this with its '7ch stereo' mode.
As far as I can tell it is putting the same signal to all the other speakers, but at the volume that you set. You can set the level of the surrounds and centre at anything from 0 to 100 in 1% increments.
I am currently running my centre at 30% and surrounds at 61%. The effect is just as you describe. A wider and deeper soundstage, yet at the same time the stage is still up front and with good localisation of individual instruments and vocals of approximately the right size.
Proper setup and attention to detail is critical for this to work well I have found... in order to avoid total shifts or other undesirable effects. But once set up right, it makes straight 2ch playback sound a bit flat and boring in comparison.
As far as I can tell it is putting the same signal to all the other speakers, but at the volume that you set. You can set the level of the surrounds and centre at anything from 0 to 100 in 1% increments.
I am currently running my centre at 30% and surrounds at 61%. The effect is just as you describe. A wider and deeper soundstage, yet at the same time the stage is still up front and with good localisation of individual instruments and vocals of approximately the right size.
Proper setup and attention to detail is critical for this to work well I have found... in order to avoid total shifts or other undesirable effects. But once set up right, it makes straight 2ch playback sound a bit flat and boring in comparison.