Laboratory test report
The Callia certainly has sufficient output to drive any following component, with Newport Test Labs measuring 3.88-volts from the balanced outputs, 1.99-volts from the unbalanced outputs and, from the headphone output when loaded down with 25Ω, a hefty 411mW. The balance between the left and right channels was outstandingly good, at just 0.011dB, while the separation between the two channels was gulf-like: 128dB at the frequency extremes and 130dB across the midband.
The signal-to-noise ratio of the Callia was also outstandingly good, with Newport Test Labs measuring 112dB A-weighted using 16-bit/44.1 test signals, improving to 115dB using 24-bit/48kHz test signals. THD was measured at 0.001% with at 1kHz CD-standard signals. THD vs. Frequency with AES-17 signals is graphed for two levels (–1dB and –20dB) with the higher signal’s distortion tracking better than 0.001% across the frequency range, and the lower –20dB signal tracking only very slightly higher. An excellent result, as you can see from looking at Graph 6.
Spectrum analysis of distortion at 1kHz at maximum output is shown in Graph 1 and you can see that there’s just a second harmonic at –130dB (0.00003%), a third harmonic at –113dB (0.00022%), a fourth at –132dB (0.00002%), a fifth at –123dB (0.00007%), and a seventh at –130dB (0.00003%). The noise floor across the audio band is down at –140dB, so the tiny amount of noise there is is primarily low-frequency.
Distortion at –20dB, which would be more typical of the levels expected when listening to music than the result at 0dB, is shown in Graph 2. There’s just a single third harmonic component at –130dB (0.00003%). Very low-level distortion (at a recorded level of –90.31dB) is shown in Graph 3. No distortion components are visible above the noise floor at –140dB.
Intermodulation distortion (IMD) was measured overall for AES-17 signals as being –108dB (0.00039%). CCIF-IM distortion is illustrated graphically (Graph 4) for CD-standard test signals of 19kHz and 20kHz. You can see there is no regenerated signal at 1kHz at all, and there are only two sidebands at 18kHz and 21kHz, both of which are down at around –118dB (0.00012%). Some sampling-related artefacts are visible up around 44.1kHz, but they’re all more than 120dB down (0.0001%).
Frequency response was ruler-flat and
extended. The CD-standard frequency response is shown in Graph 5 and you can see that it’s only around –0.01dB down at 20kHz (note the vertical scaling of 0.2dB per division). At higher sampling rates, the responses were as flat, with the frequency responses down just 0.32dB at 45kHz (96kHz) and 4.5dB at 90kHz (192kHz).
Newport Test Labs reported that de-emphasis was not implemented in the Callia, which means that CDs manufactured prior to 1989 may require a slight treble rolloff to compensate for the resulting increase in the level of high frequencies. There are no other implications.
Low-level linearity was excellent, as you can see from the tabulated results, and jitter was extraordinarily low… also excellent.
Square-wave and pulse testing showed that Prism Sound appears to be using an infinite impulse response (IIR) filter in preference to an FIR type, evidenced by the lack of pre-ringing, which is the type of filter most audiophiles report as being audibly superior to FIR or ‘brickwall’ types.
Interestingly, the standby power consumption of the Callia, at a measured 1.97-watts, is higher than the Australian standard, but at less than 2-watts, hardly significant. The interesting point is why Prism Sound didn’t keep it below 0.5-watts, which would have been easy for a DAC.
I can happily report absolutely outstanding performance from Prism Sound’s Callia DAC in every measurement made by Newport Test Labs. Steve Holding
Readers should note that the results mentioned in the report, tabulated in performance charts and/or displayed using graphs and/or photographs should be construed as applying only to the specific sample tested.