Thanks for responding Dean,

I had already tried both a dynamic and a phantom powered mic and, as noted in my original post, I had set 'Input 2 Source' to mic in the setup. The problem was that I somehow failed to register, when I read the Advanced manual while doing the original setup, that it's necessary to save the 'Input 2 Source' setting for each preset. So in other words, when I accessed presets after the original setup they were still in the default setting.