Loads of people use cables other than NACA5 & are happy with them
Not getting into the old cable debate on what sounds better, but IMO it really is hard to beat NACA5 in a Naim system, some might sound different & more pleasing to your ears in your system in your room. But overall to me it is hard to beat, especially considering the price.
But yes, some cables - I did say some - are BAD with Naim.
Naim amps - especially the old models & a lesser extent the latest models - need specific cable properties to load the amp output with correct inductance & capacitance. NACA5 is designed with this specific high inductance & low capacitance - hence the wide conductor spacing & the need to have a minimum of 3.5m of NACA5.
But getting cable specifications is not easy - try getting it from most all the manufacturers - so the customer is in a bad place to get it right for a Naim system.
Fortunately I have the tools to measure this kinda stuff.
BTW - Naim forum gives the NACA5 specs in FAQ - 1uH/m & 16pF/m
I use Chord Odyssey-2 on the SuperNait. It has 6m per channel that gives about the eq inductance of 3.5m NACA5.
Reason I use Chord was because I need to get one channel through a conduit under a fireplace & NACA5 is just too stiff to get round the bends.
My Nait-2 has 4m of Linn K20 which is a very close match for NACA5.
What does the "wrong" cable do ??
I once borrowed Kimber PR8 (which has very low inductance but very high capacitance) as a temporary hook up to the Nait-2 & it ran hot even when not running. I took it off PDQ. But it runs & sounds fine on my buddies Audiolab system.