I believe the Morrow MA3s are unshielded cables. However, I believe Mike makes a shielded cable as well, and it may be possible for him to install a shield around his MA3 design.
Based on previous discussions with Mike, I know he believes that shielding generally degrades the sound quality of a cable. I believe he uses a twist/geometry for the individual conductors comprising his unshielded cables to reject EMI/RFI. In my SET system where I am using a long (6-meter) pair of MA3 interconnects between the TVCs and 300B monoblocks, I have been lucky in that there is no noise whatsoever introduced by the use of unshielded cables throughout the system. (YMMV, I suppose.)
Based on previous discussions with Mike, I know he believes that shielding generally degrades the sound quality of a cable. I believe he uses a twist/geometry for the individual conductors comprising his unshielded cables to reject EMI/RFI. In my SET system where I am using a long (6-meter) pair of MA3 interconnects between the TVCs and 300B monoblocks, I have been lucky in that there is no noise whatsoever introduced by the use of unshielded cables throughout the system. (YMMV, I suppose.)