Effect:
A headphone amp that just sounds great. That's all it does.
Simply plug in the output of your pedalboard to the headphone amp, plug in headphones and blast your volume with the large volume knob. Play whatever you like and be the only one to hear what you're playing. Unless someone else plugs into the secondary headphone out, then you can both listen and not bother another living soul.
Sometimes it is just better to keep it to yourself.