i was asking simaudio this exact question about my p-7/w-8 combo just the other day. Their response was that they don't recommend any one specific brand of cable as results are so system, room and personal preference dependant. they did say they have used Cardas and Nordost with success in the past, among other brands. Other advice they gave me included:
1. all good interonnect cables have shielding
2. all connectors must fit tightly (althouhg not so tightly that they damage the finish on the connectors)
3. all copper cables may sound "warmer", whereas the more silver in the cable the tendancy to increase retrieval of fine detail (though deliberate/careful cable geometry can offset this)
4. in speaker cables, spades are always preferable to banna plugs as there is usually more surface contact
They also mention that, if at all possible, it is recommended to use the same brand of cable throughout the system -interconnect, speaker cable and power cords - as this provides the most synergy and therefore the most benefit.
Finally, they don't feel that power conditioners are necessary. although they told me to "go for it" if I found a conditioner that prduced good results on my pre-amp, they categorically say NOT to use power conditioners with their bigger amps.
Myself, I'm using Cardas Clear interconnects from my Marantz SA 11-S1 SACD player to my Simaudio P-7 to my Simaudio W-8. Speaker cables to my Revel Studio 2s is Cardas Golden Reference. I'm still experimenting with power cords.
