05-19-11: BadwisdomOK, I see.
Bombaywalla,
i know that Accuphase and Wadia players have this kind of digital control, but whats weird on the Pure dock is that only latest iPod generation allow for that volume control, its completely disabled on ipod touch and iphone...
And unless im mistaken, other docks also disable volume control when using digital out (wadia & onkyo for ex)
Nevertheless, here's the thing - once you extract the digital stream from the iPod/iPad/iPod Touch, you can play bit increase/decrease games with it on your own outside the iPod/iPad/iPod Touch environment. This is particularly true since the Pure iPod dock has its own DAC outside the iPod/iPad/iPod Touch chassis so they/Pure must be already inc/dec the bit width to suit their own DAC. At that point it becomes relatively simply to supply the user a digital volume control.
The situation is diff in the Wadia as they do have their own DAC outside the iPod/iPad/iPod Touch chassis - they merely buffer the analog output from the iPod/iPad/iPod Touch. They could have provided a digital volume control off the digital bit stream but they chose not to. Would have been really nice if they did....
In Onkyo the situation is still different - Onkyo made their iPod dock product specifically to mate to their HT receivers (I have an Onkyo iPod dock hence I did read the manual) - that's why there's only a digital out. I believe that the volume control is done thru Onkyo HT receiver's main volume control.