Quilter Phantom Block.

Here's a piece of gear that can save your job, and your reputation — the Quilter Labs Phantom Block phantom-powered electric guitar interface. 

Similar to a direct box, it allows you to plug your high-impedance guitar signal directly into the low-impedance mic inputs on a mixing board. But unlike a typical direct box, the Phantom Block features amp-like tone and gain controls — perfect if your amplifier fails you, or if it suddenly turns out the gig requires a silent stage with no amplifiers whatsoever. 

Whatever the reason may be that you find yourself having to go direct into the sound system, the Quilter Labs Phantom Block electric guitar interface will ensure you don't have to sacrifice your tone while doing so.