Just to clarify regarding setting the gain directly on the boards versus using a switch on the front. I have recommended for those that don't rotate gear that often to have a "gain module" inside. As decur points out, it has 3 settings but could have a 4th setting as well if all three pins are shorted. This will give the lowest gain out of all combinations.
For the ones rotating through gear often it would be a hassle to open/close the cover every time a different headphone/source is used. Hence the high/low switch on the front.
For the ones rotating through gear often it would be a hassle to open/close the cover every time a different headphone/source is used. Hence the high/low switch on the front.