Balanced connecter output voltage on a Brooklyn + DAC.

Have you tried contacting Mytek?

I've read the Brooklyn DAC+ has twice the voltage on its XLR outputs. So my guess would be it is 4V - 4.5V rms. But that's the point of the volume control, if you're connecting it directly to an amplifier. Just turn down the volume. Many amplifiers hit their maximum output at less than 2V rms input.

-6dB should cut the voltage roughly in half. Here's a dB <-> voltage calculator.