Article Index
Prism Callia
p3 Sound Quality
p4 Conclusion
p5 Measured Performance
All Pages

  The optical and coaxial S/PDIF inputs can go as far as 24-bit/192kHz. Take the USB route, though, and you can go all the way to 32-bit/384kHz (the Callia internally ‘decimates’ this to 192kHz, though). Thanks to DSD-over-PCM (DoP), you can feed DSD128 (decimated too) and DSD64 material into the Callia – a feature that’s not supported by Prism’s existing pro-use products. Note that DSD64 and 64x48 DSD variants can be received via S/PDIF, courtesy of DoP. Furthermore, a final DIP switch enables some types of DSD stream to be accommodated without the risk of clipping. You cannot fail to be impressed by such attention to detail. 




The neat internal layout of the Callia. Prism’s engineers have gone to much trouble

to prevent the different sections from interfering with each other – as the spacing

between them demonstrates.



The converter circuitry is a complex and original combination of ‘standard’ Cirrus CS4398 DAC (only the last section of which is used) and proprietary processing implemented in a Xilinx Spartan FPGA chip – shades of Chord here. Another chip, based around an ARM microcontroller, looks after the USB interface – not for Prism the usual ‘bought-in’ XMOS solution! Prism supplies the specially-written Windows drivers on a USB stick. Interestingly, DSD is converted into a form of PCM – a ‘strange shape’, says Ian Dennis – rather than being decoded directly. The reasoning – claims of better performance – is explained in a very comprehensive ‘operation manual’.


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