Breakout box with signal pass through?

[webstop]

I wonder if there is a breakout box, like Delta, Omni, C-port or Solo, that allows to route signal from its input straight into the output while computer is off?
Such box, if it exists, would be very useful at the times that I simply want to play with my synth through monitors.

 

[warlock]

It's called a mixer

Keijo

 

[webstop]

I didn't know that I can substitute a breakout box with a mixer
Besides, I have nothing to mix. Why would I want to put unnecessary device onto the signal path?
It really puzzles me how the breakout boxes that I know miss such an obviously useful feature: when the computer is on, the signal goes through the soundcard, but when computer is off, the signal goes right through the box.
I've heard of people trying to find a way to power up Solo breakout box independently from computer for exactly the same purpose.
That is why my question remains: does anyone know a breakout box with such feature?