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Sorry, I can't say much on that... my Phonitor does not get much use these days. Currently I use the DAC2 most of the time, feeding either the K812 or the DT250, or the V281 driving the Abyss. T1 goes with the A2, which does not offer any form of crossfeed, but is still my favorite with most Beyerdynamic models I have.
Major difference between Phonitor and Classic (never used crossfeed on the Daccord as the circuits are identical as far as I know and I always used Daccord + Classic) is that the Phonitor tries to emulate near-field monitors with its combination of crossfeed, angle and center settings (what SPL calls the Matrix). While crossfeed in itself is subtle on both Classic and Phonitor (can be switched to only use crossfeed without the rest of the Matrix), the effect of the full Matrix setting is very easy to spot: it does indeed narrow the soundstage down and put it on front of me, more like speakers would.
Crossfeed on the other hand is just a subtle change of perception (and that depends on the recording), with the intended effect to remove stress by softening the strong left/right separation a headphone has by its very nature. As on headphones I routinely listen to EDM and electronics that don't contain natural spacial clues, that is not of importance to me and I therefore don't use it (with my current main amps mentioned above not even offering it at all). The Matrix is easy to spot even with this kind of artificial music, but I rather like being surrounded by sound, so I did not use that either.
The Phonitor does drive the T1 well, so problem with the combination. I found the A2 to be just a bit more lively and just as detailed, while giving it a bit more prominent bass when setting the output impedance to 100Ohm. If you're considering the Phonitor I'd suggest take a look at the smaller brother, the Phonitor Mini. It shares all relevant circuits with its bigger brother, removes some studio-related features and the preamp functionality... but costs *much* less.