NAC-A5 is the 1st choice always with Naim, but especially the older pre-black models
But I agree its not easy to lay & stay around bendy bits
I need to run one channel thru a conduit under my stone fireplace, NACA5 just wont push or pull thru the 2x 45 degree bends. So I tested a number of alternatives & settled on Chord Odyssey which (IMO) is very close sonicaly to A5, plus its inductance & capacitance suit Naim & seems to be a preferred alternative in the Naim world. But it is so easy to lay, it bends easily & stays bent exactly as you left it.
Another thought is Linn K20 - this is (reputedly) the same as the old NAC-A4.
The cable spacing, general appearance & the electrical specs look almost identical to A5, but it is significantly more flexible than A5.
Its reputed to sound similar to NAC-A5, maybe slightly softer from what I remember. But it may depend more on your elegances to Salisbury or Glasgow, I once read a heated debate on how bad (or not) A5 sounded in an all Linn system. Amazing how excited we get over a few stands of copper.