People who keep changing their cables do so mainly because they never fix the underlying issues with their system, poor acoustics, poor speakers, poor speaker interaction with their room, the rare but not unheard of poor interaction between amp and speaker .... cables, unless there is something truly wrong with them, are so far down the list, it is laughable, and it is mainly the cable cult that pushes them, no matter what. For some people, every problem can be solved with a hammer.
I am a fan of Magnepan, especially if you have an untreated room. It is why they win "best" of show so much. I don't think it is because they are so obviously better than other speakers in a properly setup room, but that they work well without treatments giving them a serious edge in those situations.
Even with the Magnepan, room treatments will still help. The are less immune to floor/ceiling effects, but still need wall treatments for optimum performance, and then bass, which brings us to your subs, which don't sound too hot. Better subs, and perhaps better bass management from and equipment standpoint, are the next step up, and if done in conjunction with some basic room treatment, is going to make a difference so far beyond what any cable would ever do that it is almost laughable discussing them.
Most Magnepan users are pretty set on their speakers, but if you are willing to invest in a "room", and $900 is not going to do it, but I personally believe that the combination of flatter frequency response, even in room, and lower distortion of a good dynamic speaker can result in better sound than your 1.7i, but I will certainly give credit to the "sound" of a planer array may not give something you give up easily.