I find Naim musicality to extend to lower volumes, but this depends on your speakers as well. I honestly can't remember how the Quads sound at lower volumes - but I don't recall a significant loss of low end presence at low volume as can sometimes happen with sealed box speakers.
PS - Naim actually says this about their speaker cable:
"NACA5 is our multi-strand loudspeaker cable, consisting of two separated 4mm square conductors. Its design is optimised for use with Naim amplifiers and loudspeakers by ensuring that its capacitance, inductance and resistance are entirely compatible."
Impedance is not the proper concept applied here...
PS - Naim actually says this about their speaker cable:
"NACA5 is our multi-strand loudspeaker cable, consisting of two separated 4mm square conductors. Its design is optimised for use with Naim amplifiers and loudspeakers by ensuring that its capacitance, inductance and resistance are entirely compatible."
Impedance is not the proper concept applied here...