This thread really interests me since I have just decided to invest on a hifi audio set-up. This came after I find my current AV gear to be still wanting of the kind of sound I am looking for in so far as audio listening is concerned. This is not to say that my current Yamaha RSV1800, Onkyo CP1400 Turntable, and Boston Accoustics Horizon Speakers perform bad. In fact they are sonically pleasing and should I say more than adequate in most respects. But when compared to dedicated audio hifi systems ( Note, I deliberately used the word "dedicated," instead of "expensive"), you could sense that they still are not in the same "level," so to speak.
In my pursuit for what I prefer to be sonically satisfying system, I decided to acquire the following:
1. Dynaudio Confidence C1 speakers.
2. Plinius 9200 amplifier.
3. Rega P3-24 (fitted with Rega EXACTcartridge) turntable.
4. Used XLO Ultra 6 speaker cables.
Now my buying a used XLO speaker cable doesn't in any manner show that I believe that cables are not as important than the rest. On the contrary, after substantial time spent auditioning cables, I can sense perceptible differences in their performances. However, it is equally important to cite the fact that expensive cables are almost observed to perform better because more often than not, they are auditioned using very high end gears. But it doesn't mean that expensive cables always sound better that their cheaper siblings.
Going back to my used XLO cable, the decision to buy this was borne out of a comparison test I did versus a 100T ++ Transparent speaker cable. Only the deeper bass delivery of the Transparent was better. Everything else like, soundstage, balance, clarity, etc. favored the XLO. Note that the XLO costs only 1/10th of the Transparent's hefty price tag, not to mention that I got a 5T discount for buying it used.
In conclusion, it is important to mention that speaker cables and interconnects play an important part of your system, and that yes they do sound differently. However, price is never the determinant of its excellence or lack of it.
With regards to power cable, this is an area that I remain unconvinced as to its importance to sound improvement versus what the manufacturers of your gears already provide when you buy them. My belief here is that they should know better. Again, as in several occasions, I could be wrong.