I have the NAC-N 172XS/NAP 155 into Sonus Faber Concertino speakers.
System: 10 liters two-way bass reflex
Nominal Impedance: 8 ohms
Power Handling: 25-120 watts
Frequency response: 55-20,000 Hz, + 3 dB
Crossover: First order attenuated
Sensitivity: 86 dB/1 watt/1 m
Woofer/Midrange: 140 mm PP treated cone
Tweeter: 20 mm silk dome ferrofluid
Dimensions (H × W × D): 320 × 220 × 290 mm (12 × 8 × 11 in)
Packaged Weight: 33 lbs. (15 Kg)
I find I need to push the volume high to get the detailed Naim signature sound.
My dealer suggests swapping out the NAP 155XS for a NAP 250.2 (non DR) to solve the problem, rather than the 272XS streamer (do that later).