The Arcam, (wonderful gear), probably has enough current so it wouldn't be a problem, so you can most likely do it. However, to be safe, I might put a multi speaker switching device in line. One that comes to mind, is the Adcom. Don't know if they still make it or not. The way it works, as I recall, is that it places a 4 ohm resister in line, so the amp, sees a non reactive 4 ohm load.
This, if still available is an easy fix, and would give you piece of mind.
This, if still available is an easy fix, and would give you piece of mind.