For the vast majority of headphones, the Mojo 2 will directly power them with plenty of headroom. The Mojo 1 is slightly more powerful and will power all headphones including my Susvara, infamously the hardest to drive headphone.

In fact, an amp can only decrease the fidelity of the chain. Since the Mojo has its own full powered and digitally adjustable output stage, you should indeed just use that directly.

I could see the argument that since the Mojo 2 can’t power a Susvara or HE6 with much headroom, they’d want to put an amp in the chain in case someone walks in with one of these but still…