The ADI-2/4 Pro SE uses the third entry (red LED) of the included MRC. AD is ES9822Pro, DA is 2*ES9038Q2M. As KaiS explained there are other things that make the difference in real world applications. For example we improved the existing hardware reference levels in two ways: full coverage and one step more (+1, +7, +13, +19, +24 dBu). And made sure that the lower ref levels reach the max in SNR by attenuating at the output (including the self noise of the output opamps).
That gives better results in real world usage than implementing one (two) overpriced ES9038Pro. Which wouldn't fit in here for various other reasons anyway.
Same for the headphone output. Less THD plus less self noise made it possible to add a third power output setting called IEM (max +1 dBu). Should be self-explanatory.
The new ref levels are found everywhere - headphone out is now +19 dBu for high power and +7 dBu for low power. Since the unit has 2.5 dB digital and analog headroom the former +22 dBu is not needed, you can easily reach those scary levels by just upping the volume control.
While working on this new unit we also have ideas that might be ported back to the existing units. For example when trying to minimize power consumption. This might come in a later firmware update.
The biggest difference between the ADI-2 Pro and 2/4 Pro was not properly communicated on these 'pre shows'. As the name indicates the 2/4 has 2 balanced inputs and 4 balanced outputs. Other than the original Pro it can do balanced phones output on DAC 3/4, while DAC 1/2 still feeds the rear XLRs with whatever signal. This removes several limitations and even simplifies operation. To not lose performance (check the description of the Advanced Balanced Mode in the manual) we now use a True Balanced Mode, where the balanced configuration is reached by 3 double relays that change the balanced (or differential) connections between DAC output and the 4 headphone amp inputs so that unbalanced stereo turns into balanced stereo. No phase shift circuit or other electronics are added to the signal path for this.
The additional Pentaconn socket (4.4 mm) is balanced only and switches the phones out to balanced automatically when inserted. In this state it is still possible to use the front TRS and grab the same high quality signal (balanced with up to +28 dBu) as line signal (while you could plug in unbalanced headphones it doesn't make any sense as the TRS signal then is not stereo but out-of-phase mono).
The TRS on the rear can be switched from source DAC 1/2 (default) to source DAC 3/4 (another relay). This was requested from mastering studios where the ADI is used to add an analog insert for external FX. The phones still work (even balanced), but volume control is the same then (obviously), except for the ref levels that are independent.
A Trigger Output makes it possible to connect any device with trigger input and switch on/off all devices with the ADI's remote simultaneously (power amps...).
There is more to say about the 2/4 Pro SE. Stay tuned.