I have an H360. Next to the USB input, there’s a mode switch. I saw that the HD30 also has that switch. The HD30 manual does not explain what the switch does, but the H360 manual does:
USB Mode Setting:
The USB mode selector switch on the rear
panel determines the mode setting of the
USB audio interface. Please note that the
USB connector must be disconnected
before changing this setting.
With the switch set to “A” (default), the USB
audio interface is set to plug & play mode,
and up to 96kHz and 24bits resolution can
be achieved.
With the switch set to “B”, the USB audio
interface can achieve up to 192kHz and
24bits resolution, and native DSD64 and
DSD128. B mode is plug & play when using
MAC, with the exception of DSD. With DSD
you need additional software, please consult the H360 section of the Hegel website.
If you are using a PC, running a Windows
operating system, an additional driver has
to be installed on the computer for booth
PCM and DSD. To download and install the
driver, please consult the H360 section of
the Hegel website.