Thank you all for your input.
Perf, the amp I got (yesterday) is second hand and is almost 3 years old. So the recap is not for a few years yet. The object of my quest was to know if, and how much, merit I should give to Naim's warnings and some dealer's scare tactics to the effect that this may cause the amp to blow-up and that the warranty would be void. Apparently, this has been the dealer's experience in this case with my particular brand of cables. So he claims...
Presently I use Transparent Audio Laboratory's MusicWave speaker cable and can't really complain about anything. Then again, I haven't compared it to anything else, so I wouldn't know what I'm missing, if anything. Since all this is relatively new, or recent, I was a bit worried for the long term effect.