The Sensitivity and Line Out knobs should have pull switches. I suggest pulling them out to make the sound a bit more lively.
My line level knob doesn`t have a pull switch (just sensitivity does).
I tried my acoustic bass (think upright) with Monique and my Eich T500 (on a Barefaced Big Baby) but I don`t think I got an improvement over the T500 alone. I mean I prefer the sound of the T500 alone but I dig the Monique in headphones. I guess they don`t pair well for acoustic. Is this a case where I would have a big advantage using a power amp instead of the Eich?