Thanks to Laurent for this report. On the French AppleStore, on the
iPod Hi-Fi-dedicated webpage one can read that this new device can be powered thanks to 6 watch-type batteries... Of course it is impossible, the Type D batteries are the largest batteries of their class, 6 of them weight close to 1 kg.
Hereafter is a photo of Martin leaving the Shibuya AppleStore (Japan) with an iPod Hi-Fi.

PS: we now understand why Apple has reduced the size of boxes for the last computer models... it is to save space in stocks for the iPod Hi-Fi boxes :)