I'm using a PASS X250.5 Amp. & PASS X1 Preamp. to drive a pair of Wilson Audio Sophias, and this combination sounds excellent - and is as good as is sensibly needed for near reference listening in a normal size room. My Source is a Krell SACD Standard MK3, and I'm using inexpensive Transparent Plus Series Spkr. Cables, Canare XLR ICs, with OEM 14-AWG Power Cables (same gauge as in-wall AC Cable).
When setting-up this System, I experimented with very expensive Cables borrowed from local dealers, and I found the sonic differences to be negligible, if any could be heard at all, for the most part there were no real discernable sonic differences especially amongst Cables in which the Conductors were made from the same material(s), of the same gauge, with good connectors and of quality build.
My local Dealer has a Demo. System currently set-up in his Shop consisting of Krell Evolution Electronics and Wilson Audio Sophia Speakers, and it sounds freakishly-good/scary-real. When I asked him about the Cables he told me whatever is lying around the shop and for Power Cables he uses whatever the manufacturer sends with the Components obviously not overly concerned about Cables.
Whenever I bring up the topic of Cables to the Guys at PASS, Wilson and Krell, I always get an initial laugh which says a lot about what is really important in a System the Components (+ Listening Room).
I cant imagine parting with a Statement (mega-buck) Component that I really like, just because I thought that it didnt sound right with a certain Cable...