Most compatible speaker/interconnect and power cables with ARC ref system?

Hi guys

Some advice please. I have just joined Audiogon and would really appreciate some advice. I have 2 audio research Ref 250 amps, Ref 10 pre-amp, ref 9 CD player, Naim music server and a Cary 500 music streamer and transparent power conditioner. My speakers are sonus faber Ellipsa SE's which were developed using this ARC ref system. I would very much like to get the most out of the system, as I love the warmth of the valves and the transparency of the sound. Anyone have a similar setup or just have advice on most compatible speaker cables and interconnects, and which interconnects are the most critical? Does the power cable make such a big difference to warrant the high price of some of them? Some articles seem to rubbish expensive power cables and say it makes the least difference of all.