Hi Don
Since the iFi is portable I would use a cord with 3.5mm plug on it, to keep the portable rig lighter and less clunky. Then add the heavy brass 1/4" adapter when plugged into the stereo, or leave the adapter plugged into the stereo so I wouldn't lose it!
My older AKG K701 cord is opposite, with a 1/4" plug "for professional use"

so I have to use the adapter with my portable. No biggie. Clean the adapter connections once in a while to avoid clicking, etc
Rich