Naim 5i: How important are Naim NACA Cables?

I don't own a Nait, but a very good and trusted Naim dealer recommends the NACA5. He sells far more expensive cables, so it's not a sales pitch. He feels there are better speaker cables out there, but with the Nait/NACA5 combo, you have to spend a ton of money to get a true improvement. Different cables will sound different, but the NACA5 is hands down the way to go in his opinion.

I know this because I was very close to buying a Nait, and have spent a lot of time in that shop. He's a very down to earth guy who thinks system synergy is the most important thing (other than the music).

Thanks guys - that's just the kind of information I'm looking for. So far, here on agon, even split. The seller tells me that the NACA is quite critical, but I can't use it in my system. My speakers take only spades, and the run is about 18', too long for NACA. This is for a bedroom system - Jordan singlel driver speakers, and the only place for the amp is on the nightable - no moving stuff around. If any one else has done this experimentation, please chime in. I too will be using the Bluejeans speaker cables.

Thanks again for your input, Peter

Peter,
I was a long time Naim user and hung out on the Naim forums for quite some time. Strongly recommend using the NACA speaker cabling.

I am using Transparent MusicWave speaker cables with a Naim NAP 250-2. Here is what Naim has to say about the topic (from their forums):

Alternative speaker cables are not recommended by Naim, however, should you still wish to try them then you should ensure that the cable is low capacitance and of moderate inductance. High capacitance cables are to be avoided at all costs and may result in damage to your amplifier.

NACA5 specifications are as follows:

Capacitance: 16pF per metre
Resistance: 9 milliohms per metre
Inductance: 1uH per metre

Minimum length: 3.5 metres per channel
Maximum length: 20 metres per channel (note that longer lengths can be used up to around 25 m but then some small signal loss must be expected)

And this is what Transparent had to say about their MusicWave cable when I asked:

The MusicWave speaker cable by itself has specifications that are fairly typical for a twisted-pair, 12 gauge copper speaker cable.  It is not a high capacitance cable design which Naim warns against using, but it is not as low in capacitance or as high in inductance as the parallel, spaced-conductor design of the Naim speaker cable:
 
Musicwave raw cable
Series Loop Resistance approximately 9 milliohms per meter
Series Loop Inductance approximately 0.5 uH per meter
Parallel Capacitance approximately 120pf per meter 
 
 
One of the functions of the network in MusicWave speaker cable is to limit the upper bandwidth of the cable to about one million cycles.  We do this primary to prevent the cable from acting as an antenna for radio frequency noise but this also brings the electrical performance of MusicWave closer to the high inductance Naim speaker cable design.  What we are doing with the network in the MusicWave cable accomplishes essentially the same thing as the Naim speaker cable which uses a long length (3.5m -20m) of high inductance cable to achieve an ultra high frequency roll off.  One of the advantages of using a Transparent speaker cable with a Naim amplifiers is that we can achieve a similar high frequency roll-off even with a short run of speaker cable.