DI Box or Not?

Clearly there is a lot of discussion about this on the webbernets.

I currently run a USB keyboard into a Focusrite Scarlett 18i8 audio interface with Dynamic Range (Line Outputs) 108 dB (A-Weighted). Those outputs are fed into the AB168 dSnake, and then the QU-32 does the heavy lifting.

My contention is this. As long as the 48V is disabled on the board, I’m not at risk of damaging the outputs on my audio interface. Is this a true statement?

Also, there seems to be no reason to run a DI box between the audio interface and the dSnake.

Opinions?

Thanks!

You’re plugging a balanced low impedance signal into an input designed for balanced low impedance signals. As long as the maximum signal level doesn’t exceed the maximum input level of the input (which it doesn’t) you don’t have a problem, you’ll need the pad though, or turn down your interface outputs slightly. It may even by able to tolerate phantom power from the console if it has DC blocking capacitors on the outputs, but you’d need to ask Focusrite about this. You should also be able to lift Pin 1 if necessary to get rid of any humming.

Many people who think this needs a DI are thinking “1/4” connection = DI" simply because instruments use 1/4" connectors and those need DIs, without considering why that is and the electrical characteristics of the signals.

Chris