You could take a cable from one of the output capable DIN sockets (Tape, AV, Aux 1) on the 282 to connect to the MH150. You’ll need a suitably wired DIN5 to 2xRCA cable.
As you say you could use also use the digital output on the NDX2 and use the DAC in the MH150 but you’ll need to go into the settings on the Naim app each time to enable and disable the digital output on the NDX2. It’s not enabled when the normal analogue outputs are in use.
More info here in the FAQ on connecting headphone amps to Naim kit.