My understanding is it is at a much lower price point, but I don't know the details. I guess in order to do that some parts had to be cut. There's also these.... From the manual...
Page 19:
"The ADI-2 DAC processes all audio in the digital domain. Having only one stereo digital to ana- log converter, different settings of volume, equalizer or effects for the three outputs is not possi- ble when used simultaneously (the ADI-2 Pro has two DACs, therefore can process two stereo signals independently with different settings)"
Page 34:
"The rear RCA and XLR outputs and the front outputs Phones and IEM are fed from the same DAC, hence carry the same signal. They all have individual driver stages with different output levels, see next chapters for details"
So that's a little disappointing, as I liked the idea on the ADI-2 Pro of running a crossover internally using the PEQ on the rear 1/2 XLR outputs to main speakers, and the front 3/4 ones to subwoofer. That wouldn't be possible with only one DAC chip of course.
But all that said if the price is right it's very attractive - and frankly the addition of a remote is a big deal for some, including myself.