Emotiva Big Ego User Manual page 9

USB Modes (technical)
In order to deliver the absolute best performance and
the ideal level of convenience with the widest variety of
computers, your Big Ego supports two different USB audio
modes - UAC1 and UAC2 (this is not the same as USB 1.0,
USB 2.0, and USB 3.0).
The Big Ego's default operating mode is called USB Audio
Class 2 (UAC2), which supports all standard bit depths and
sample rates up to 32/384. The drivers needed to support
UAC2 are built into all modern Apple computers, but not
into Microsoft Windows, which is why you have to install
our drivers to unleash the full potential of the Big Ego with
a Windows computer. Some versions of Linux also support
UAC2, but not all.
Since it isn't always convenient to install drivers on a
Windows computer, the Big Ego also gives you the option
of running in USB Audio Class 1. Both Apple and Windows
computers have support for UAC1 built in, as well as most
versions of Linux, so you can use UAC1 on most computers
without drivers. The only limitation is that UAC1 only
supports bit depths and sample rates up to 24/96k.
The Big Ego's UAC1 mode is engaged by holding down the
Filter Select Switch button while connecting the Big Ego to
the computer, and the USB Mode Indicator LED will light up
red when the Big Ego is in UAC1 mode.