This thing is so fraught with potential problems. For one thing, I assume the same (physical) amp and speakers will be used. This means that for quick A/B they will have to hook it up to a switchbox. Which I doubt will happen, because that means another run of cable from amp to switchbox. And the question of the switchbox itself, effect on capacitance, etc. If they don't use a switchbox, it means they'll have to disconnect the amp and speakers every time a switchover happens. Which means powering the whole system off. Which means several minutes delay, associated warmup and more doubts.
I just don't see this going smoothly at all....plenty of room for either party to cry "foul" afterwards. Meantime, they'll both get tons of publicity for their web sites....maybe that's all either of them wanted. It bugs me that the guy who took the challenge is one of the big 'celebrities' in high end audio.