Speaker cable recommendation McCormack/Maggie

Looking for a pair 6-8 ft speaker cables to go between a McCormack DNA-1 Deluxe Silver Upgrade (with Jensen isolation input transformers) and a pair of Magnepan MMG stock speakers. Currently using generic Monster 12 gauge.

I know it is often reported that speaker cable is not an area of concern for RFI unless you live in a high RFI zone. Well my house is sandwiched between an AM transmitter less than 2 miles away on one side and an FM transmitter less than a mile away on the other. I have been chasing down a sibilance/harsh high end problem since I moved into this house 2 years ago. Same speakers and wire in my old house did not exhibit this behavior at all. After switching out every piece of gear in my system, I have come to the conclusion that airborne RFI is the culprit. When using unshielded ICs (Morrow MA-1) I can hear the local AM news station over my speakers. When using heavily shielded ICs (BJC ICs) radio station goes away but sibilance remains. I am curious to see how speaker cable may influence this issue.

I have done a lot of forum reading, but still cannot seem to hone in on 2 or 3 brands to try out. I hear good things about Alpha Core Goertz with Maggies, but some complain of sibilance due to poor RFI rejection. I hear good things about Reality Cables, but some say they are not a good match with Maggies. I have heard Anti-cables are a good match for Maggies, but may RFI prone. Straightwire, Signal Cable, Element Cable (Risch recipe), Heartland Cable, Kimber, Audio Art, Purist Audio, I have heard good and bad things about all of them. What I need is to hear some experiences with Maggies in a high RFI zone. Does speaker cable make a difference in terms of RFI?
Can you do your own shielding of some sort. Wrapping the already shielded cable in some dielectric tape then build a farrady cage so to speak out of a conductive material tape. Or would that just backfire? I don't know>
I have used McCormack DNA- deluxe monos with MG1.6QRs. I don't have the unusual RFI problem you have, but I do have a couple thoughts. If I read your post right, in your former location with a given set of equipment, you had neither sibilance nor AM signal pick up. Changing IC's solved the latter problem in your new house
Keep in mind that the sibilance could be due to the room. When I moved eight years ago, I had fits trying to get my Maggies to sound right in my 17 x 21 living room. Sibilance was very noticeable in the new house, whereas it had not previously been a problem in my much larger great room. It took both room treatments and a new source to loose the sibilance.
That said, I used monster cable with my maggies for a very brief period (waiting for new cables with proper termination for new amps) and they were just simply dreadful with the Maggies. I don't know if replacing the monsters will put and end to the sibilance, but I suspect you will notice a marked improvement.
I currently use anti-cables, but that may be asking for trouble with your RFI. I have also used Signal Silvers, and they were almost as good as the anti-cables. There are a lot of people who swear by the Alpha Cores, and I would like to give them a try some day. Given your situation, it might be worth using the Cable company to evaluate multiple brands.