The Ares Preamp is an adaptation of the preamp section of the Echoplex EP-3 tape delay first released in 1970. The Echoplex was a popular tape echo, but people noticed that even with the unit in bypass mode, it did wonderful things to a dry guitar signal.
Internally, it’s a fairly simple JFET boost, but it colors the tone in such a way that you really notice it when it’s off. It does provide a slight boost but it is primarily a tone-shaping tool.
The EP-3 circuit was modified slightly after serial #9450 to add a bypass capacitor to the FET stage. (There are a couple of other tweaks but this one has the biggest effect on the tone.) I made this capacitor switchable so you can easily choose between the two versions. On the other side of the switch is another much larger bypass capacitor that increases the boost potential and fattens up the signal.