yup, wouldnt take up much space, it may even save space overall.
more info if desired
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Edited by qusp - 8/23/12 at 1:03am
Given the published specs of the dx100, (which are a little vague) i'd say they are already using a similar circuit in that. the dac chip itself only needs multiple +1.2 and +3.3v voltages, probably similar for the clock, they are likely using a 3.3v clock generator. the only thing that will need more in either unit is the I/V convertor and amp section, perhaps the display may use +5v. the ESS because of only having positive supply voltages, means that its balanced output swings around a DC offset of 3.3v/2 (1.65vdc) rather than 0v. This can be cancelled in a number of ways in the output stages, but to avoid output caps they need a negative supply.
What it does mean however, is that the Japanese version will be using a virtual ground rather than a split battery with a real center tap like i'm assuming they use in the dx100. What this means is that the impedance to ground and current handling of the ground/return path for the headphones will be better/cleaner in the dx100, as its only limited to the current capability and impedance of the battery/ground plane. The virtual ground impedance and return current capability of the Japanese version, will be set by whatever DC convertor/device and caps they use. the power to source current is limited by and equal to the ability to sink it, ground is at least as important as the signal connection; myself I see it as more important.
as such I would take the dx100 over the Japanese version, there will be other trade-offs there too. having a split supply and real center tap means that they need to have some way of balancing the cells during charging, you know, so they dont go all explody from over or under charge on the negative rail. the Neg rail will have a lower power draw than the positive rail, as the dac, clock, digital circuits and half the output stages are all running on the positive rail, while only the negative going swing of output stage is using the negative rail. This means that the cells negative of center will not drain as quickly as those on the positive side.
with all that sorted its preferable to have a split supply, but it does present some obstacles to overcome and perhaps added expense, so the Japanese version may not present an upgrade at all, rather a compromise.