Manual

1.15
Operation Manual
© 2016 Prism Media Products Ltd
Revision 1.01Prism Sound Callia
DIP switches 3, 4 optimise the headphone amplifier for different headphone impedances:
When ON,ON (default): Headphone amplifier is optimised for medium-impedance headphones (32-
50S); line outputs are muted when headphones are plugged in;
When OFF,ON: Headphone amplifier is optimised for high-impedance headphones (>50S); line
outputs are muted when headphones are plugged in;
When ON, OFF: Headphone amplifier is optimised for low-impedance headphones (<32S); line
outputs are muted when headphones are plugged in;
When OFF, OFF: Headphone amplifier is optimised for medium-impedance headphones, and
headphone-sense line output muting is DISABLED.
4.2.2 Fuses and ratings
TO PREVENT SHOCK HAZARD, THE CALLIA HARDWARE SHOULD ONLY BE
OPENED BY QUALIFIED PERSONNEL. REMOVE THE POWER LEAD FROM THE
UNIT BEFORE REMOVING THE TOP COVER.
Fuse locations and ratings are as follows:
FUNCTION
LOCATION
TYPE
Mains
Rear panel
500mA(T), 20mm, glass
Note that no fuses or any other user-serviceable parts or options are located inside the Callia
unit.
4.3 Inputs and outputs
Callia accepts digital audio inputs via USB as well as RCA and optical (TOSLINK) S/PDIF
connections. Stereo analogue outputs are via RCA and XLR connections, as well as on a front-panel
headphone jack.
In common with Prism Sound professional converters, the analogue parts are of Callia are
galvanically isolated from the digital parts and the PSU in order to eliminate interference from the
analogue line and headphone outputs.
USB input
When connected via USB, Callia appears as an asynchronous USB Audio Device Class 2.0 (UAC2)
device, and supports PCM at standard sample rates between 44.1kHz and 384kHz, and wordlengths
up to 32 bits. DSD, formatted at DSD-over-PCM (DoP) is supported at bit-rates of 2.8224MHz
(DSD64) and 5.6448MHz (DSD128), plus 48kHz-multiple DSD64 and DSD128.
As a UAC2 device, Callia is supported natively by Mac hosts running OS X - so no driver software
needs to be installed, but software installation under OS X is nonetheless recommended in order that
future firmware update is supported (see Software and firmware updates). Windows does not
natively support UAC2, so installation of the Prism Sound UAC2 Windows driver is essential. See
the Installation procedures section for details.
As an 'asynchronous' UAC2 device, Callia operates from a high-stability low-jitter local clock
reference when sourced from USB.
Note that the Prism Sound UAC2 Windows driver does not currently support simultaneous operation
of multiple Callia (or other UAC2) units connected via USB to a single host PC.