Prism Sound is a UK based digital audio manufacturer known best for their professional recording hardware used in recording studios around the world.

Their products include digital recorders, editing workstations, test and measurement equipment and, most relevant for this review, multi-channel DACs and ADCs. Their modular ADA-8XR multichannel AD/DA converter unit is a benchmark for high quality ADCs and DACs in the recording industry. Prism Sound has recently turned their pro audio skills to the consumer high end market with the new Callia DAC. This DAC takes advantage of Prism Sound’s engineering capabilities to put a lot of that pro audio technology into a consumer DAC. The Callia offers 24 bit PCM at up to 384 kHz sampling rate (32 bit for the USB input), plus DSD up to DSD128. All inputs take advantage of Prism Sound’s CleverClox hybrid PLL clocking circuitry with very low jitter, better than 50 ppm. The analog signal path is fully balanced, with a defeatable volume control for the preamp outputs in addition to a high quality headphone amplifier with a real analog volume control. Everything about the Callia, from the engineering and build quality to the features offered says “professional,” without any audiophile silliness.



  • Superb sound quality, with excellent timbre and depth combined with lots of detail and sharp focus.
  • Real, honest, professional recording studio engineering and build quality.
  • A solid feature set with all the technology you need, without any “bells and whistles.”
  • Reasonably priced given the engineering and sound quality.

The Prism Sound Callia DAC

Headphone output:

6.3mm stereo jack socket, with analog volume control

Analog line outputs:

XLR male for balanced connection; RCA sockets for unbalanced connection

Selectable Line volume control enable/disable, DSD headroom select, headphone impedance select
Mains power:

3-pin 6A IEC inlet

Output amplitude:

XLR: 0dBFS=14dBu; RCA: 0dBFS=2Vrms

Output impedance:

50 Ohms

Total harmonic distortion:

-107dB (0.00045%, -0.1dBFS)


-106dB (0.00050%, -0.1dBFS)

USB Input Interface protocol:

USB Audio Device Class 2.0 (UAC2)

Audio formats supported:

44k1, 48k, 88k2, 96k, 176k4, 192k, 352k8, 384k PCM at word-lengths up to 32 bits DSD64 and DSD128 in DoP frame, also 64x48kHz and 128x48kHz DSD variants

S/PDIF Inputs Interface protocols:

S/PDIF (RCA and TOSLINK); RCA also accepts AES3-ID Audio formats supported: 44k1, 48k, 88k2, 96k, 176k4, 192k PCM at word-lengths up to 24 bits DSD64 in DoP frame, also 64x48kHz DSD variant


285x242x50mm including feet, Weight: 2.1kg.




Prism Sound


PrismsSound, Prism Sound Callia DAC, Sound, Prism Sound Callia DAC Review 2018

Design and Setup

Because of an equipment backup at home, I decided to listen to the Callia at work with my headphone setup on my desk. This setup consists of JRiver Media Center and a ASUS Xonar Essence STX sound card outputting a 24 bit 192 kHz SPDIF signal via the coaxial output. The Callia served as the DAC for the entire test, with headphone amp duties split between my venerable Schiit Asgard 2 amp and the internal Callia headphone amp. I used my normal Sennheiser HD600s and the HiFiMan RE-800s which I recently reviewed here.

Prism Sound’s excellent packaging for the Callia

The Callia came in some notable packaging. The box was one of the nicer ones I have seen, with a heavy duty plastic and fabric reinforced box and lid, and die cut foam for the DAC and accessories. It looked more like a storage case than packaging, likely from the pro audio world where you’d actually want a storage case. The DAC itself looks like a cross between the typical Hi-Fi DAC you’d expect and a piece of professional studio electronics. The Callia has many more status indicator lights on the front panel than normal, and some extra goodies on the rear panel. I particularly liked the front panel indications of the SPDIF/DSD signal type. Many modern DACs have no indicator lights at all. With computer audio, it’s very easy to have your streaming app or OS misconfigured to send the wrong signal to the DAC. In my case, I had my Tidal player misconfigured. It was downsampling everything to 16-bit 44.1 kHz, even when 24 bit 96 kHz MQA was available. The front panel on the Callia told me that straight away. The front panel has a pushbutton that serves both standby and input select functions, a ¼” headphone jack and two volume knobs. The smaller knob is the analog potentiometer for the headphone amp. The larger knob controls the digital volume control for the line level outputs. This feature is defeatable on the back panel. A set of DIP switches allows the user to activate or deactivate the digital volume control, set the headphone impedance and line level muting behavior when headphones are plugged in and adjust the DSD headroom setting (trading off noise floor vs potential clipping on DSD recordings). The configurability offered by the DIP switches is unusual and very welcome. The rest of the back panel is as expected, with balanced and single ended line level outputs, coax, USB and Toslink inputs, an IEC power jack and a fuse.

The Callia rear panel with DIP switch bank to configure DAC behavior.

Inside, the Callia makes use of Prism Sound’s pro audio experience. The chipset is the well regarded Cirrus Logic CS4398, with a lot of care devoted to its care and feeding with power filtering, noise shaping and upsampling. One of Prism Sound’s key technologies is their CleverClox reclocking systems. Most reclocking slaves an internal crystal oscillator to the input clock using a narrow band phase lock loop (PLL) to reduce jitter. The high frequency jitter performance is dominated by the crystal oscillator, with the low frequency clock behavior matched by the PLL. The problem with this is if the external clock is too far away in frequency from what the PLL expects, the loop can’t lock and jitter makes it through. This can be a problem with computer audio, where the clock from the computer audio source can be far enough out to cause problems. Prism Sound’s proprietary method generates a new, low jitter clock from any incoming clock regardless of frequency. Of course, exactly how this is done is Prism Sound’s special sauce. They do not publish the details.


Secrets Sponsor

As stand-alone DACs get better, differences between them become more subtle. I will compare the Callia directly to the two DACs I own and could compare to directly: the Schiit Bifrost Uber and the Oppo Sonica. I personally would not trust any DAC comparison based on memory, unless big differences are involved. The Callia in principle should be better because it is considerably more expensive than either of the two DACs I just named. The first thing that hit me with the Callia is that it fused some of the best traits of the Oppo Sonica and the Schiit Bifrost. The Oppo has incredible detail, resolution and sharpness. The Schiit gives up detail, resolution and transparency, but has a presentation with very big, round, 3D images. Sometimes the Oppo DAC can sound a bit flat and analytical with less than optimal source material. The Callia offered the best of both worlds here. The detail extraction, transparency and resolution were all excellent, just as good or better than the Oppo. But at the same time, every recording I could find offered big, 3D images, never sounding flat. I prefer relatively simple vocals to test this sort of thing. It’s very easy to tell if an isolated voice sounds realistically 3-dimensional. With some DACs (the Sonica is one) the presentation of the voice can be too sharp. The image is too small, point like and precise to sound fully natural.

Bebel Gilberto

Bebel Gilberto “Bebel Gilberto”

I listened to Bebel Gilberto’s eponymous album, and Emiliana Torrini’s Fisherman’s Woman. The Bebel Gilberto album is more produced, with lots of multichannel mixing. Fisherman’s Woman is Torrini and a guitar, and that’s it. The sound of the Callia shined the most on the latter album, where the image size of both the voice and guitar were admirably realistic, with real size, shape and depth. I guess this is what some of the other audio rags call “palpable” if you like words like that.

Emiliana Torrini, Fisherman’s Woman

Emiliana Torrini “Fisherman’s Woman”

With the Gilberto album, the production limited the amount of depth that was there to display, but the Callia was definitely a bit less “flat” than the Oppo. And compared to the Schiit Bifrost, detail extraction was superior. Of course, the Bifrost is under $500, so you can’t throw too many stones. Not that the Bifrost was bad, but I did want to keep turning the volume up to hear the same detail. The extracted detail combined with the large, 3D images really delivered that “hauntingly realistic” midrange that you’re looking for when listening to female vocals.

In terms of the extremes of the frequency spectrum, the Callia also did a great job. The subterranean bass on the out of print EM:T 0094 track Anthropomorphic by the British ambient electronica band Qubism had pant-shaking extension (or as pant shaking as you can get through headphones) with excellent agility and tonal quality.

EM:T 0094 Various Artists

Qubism “EM:T 0094”

On the high frequency end, vocal sibilants are what really does it for me. What I’m looking for is extension, smoothness and detail without sounding harsh or brittle. The Callia did an excellent job on this end too. Again, the female vocals of the albums above are the best examples. Especially in the simpler of the two recordings, poor treatment of sibilants would be really obvious.

Calexico, Feast of Wire

Calexico “Feast of Wire”

It’s also a sign of good DAC performance if switching to high bit rate version of a recorfing improves things in this department significantly. This means the DAC isn’t getting in the way of the improvement delivered by the increased sample rate moving the anti-aliasing filter well away from the audio band. I listened to Calexico’s Feast of Wire on Tidal in both standard 16 bit 44.1 kHz and MQA based 24 bit 96 kHz. The high bit rate version clearly improved the smoothness and detail of the sibilants in Joey Burns’ vocals.

On The Bench

Measurements were made with my M-Audio ProFire 610 firewire audio interface and Spectra Plus FFT software. I drove the Sonica DAC with a 24 bit, 192 kHz SPDIF signal from the coax outputs of the ProFire 610, and measured the analog output of the left balanced output. The signal was input to the DAC as 0 dBFS, with the gain of the sound interface input tuned to deliver the maximum dynamic range.

Careful readers will note below that many of these measurements look almost identical to last year’s review of the Oppo Sonica DAC. Why? Because both these DACs are good enough that the measurements you see below are dominated by the performance of the ProFire610 interface. So it’s basically impossible to make any meaningful conclusions from the plots below other that treating them as upper limits. The Callia performs better than the audio interface, as did the Oppo.

THD+N spectrum with 0 dBFS 60 Hz tone

THD+N spectrum with 0 dBFS 1 kHz tone

THD+N spectrum with 0 dBFS 10 kHz tone

Distortion spectra are as good as I can measure, with THD+N numbers of around 0.004%. This is about 10 times worse than the claimed THD+N from Prism Sound which makes sense. The real THD+N is being masked by the 10 times stronger THD+N of the audio interface.

The measurement gets very slightly worse with a -5 dBFS input signal, but this is just a signal to noise issue. The primary tone decreases in amplitude but the harmonic distortion peaks remain the same.

THD+N spectrum with -5 dBFS 1 kHz tone

Intermodulation Distortion (IMD) was measured with 19 kHz and 20 kHz tones. The A-B peak of 1 kHz is over 100 dB down from the primary tones. The sidebands of the primary tones are about 90 dB down. This results in a measured IMD number of 0.004%. Again, this is likely dominated by the audio interface.

IMD measured with 19+20 kHz 0 dBFS tones

Frequency response is flat as a pancake as expected. The gentle rise towards high frequencies is again the ProFire 610. The noise floor of the Callia decoding digital zeroes is at the noise floor of the audio interface, once again.

Frequency response measured with 0 dBFS white noise

Noise floor measured with digital zeroes

So the Callia is better than my tools, and almost certainly every bit as good as Prism Sound claims. This not only shows how good modern DAC engineering has gotten, it also shows the limitations of using consumer grade audio interfaces to measure them. It would be wonderful If every Secrets reviewer could have access to an Audio Precision analyzer like our Editor in Chief John Johnson, but the cost doesn’t make that a reasonable possibility.

Secrets Sponsor


Given the build quality and engineering that has gone into it, the CALLIA is an excellent buy, assuming it’s lack of streaming features isn’t an issue for you.

  • Superb engineering and build quality.
  • Lots of adjustability and very good display information.
  • Decodes all the SPDIF and DSD formats you may want to play.
  • Excellent headphone amp with analog volume control and digital main volume control for use as a preamp.
  • Hard to find combination of a big, round, 3D presentation with lots of detail extraction
Would Like To See
  • A remote control or phone app for use as a preamp.
  • Maybe some more advanced Ethernet/Wi-Fi streaming features for those of us who don’t want to use a computer with the DAC.

The Prism Sound Callia is an excellent DAC for those of you looking for a well-engineered, well-built, superb sounding DAC without all the streaming bells and whistles found in many modern DACs. Every bit of the Callia is engineered to deliver the best possible sound quality at its price point. I confess I did miss the convenience of Wi-Fi streaming in some applications, but in a system where that isn’t needed, the Callia is a really great DAC that combines fine detail extraction and resolution with a very realistic, 3D presentation. I highly recommend you give this DAC a listen if it’s feature set fits your needs.