There are CD players with a usb input for an ipod you could use. The best reason to get a dac, however, is not to play music from an ipod but from a computer. The usb input will do that on the RR2150 but there are better quality dacs you can use as well.
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macmini (as server) -> Logitech Squeezebox -> Outlaw RR2150 -> PSB Imagine B, Beyerdynamic DT880