SPL Diamond DAC Review
Craig Joyce is charmed by this stripped-down, minimalist DAC with pro audio roots…
AUD $4,299 RRP
The blurring of lines between pro audio and hi-fi is nothing new. It has been going on since the early days of amplified audio through innovators like JBL and, more recently, with manufacturers like Benchmark, Bryston and Kii Audio. SPL's new Diamond DAC taps into the company's pro audio pedigree to offer a consumer version of what you'd typically only find in professional recording and mastering facilities. So, does it deliver?
The Diamond DAC is the latest addition to the SPL's 'Professional Fidelity' portfolio, which includes preamplifiers, headphone amplifiers, power amplifiers, an analogue crossover and a phono preamp based on SPL's proprietary VOLTAiR technology – more of which later.
It's a straightforward, old-school design with little more than a fascia-mounted volume control in terms of convenience features. Alongside two coaxial and two optical digital inputs, you get USB-B and AES digital ins, plus an external BNC clock input. There's a choice of unbalanced RCA or balanced XLR outputs, each with 75-ohm output impedance, which can be set to fixed (unity gain) or variable – via a pair of dip switches on the rear panel.
With no Ethernet connectivity or inbuilt streamer, the overall aesthetic of the device is utilitarian and purposeful – this DAC exists only to change digital data into analogue audio. Should you seek a preamplifier with analogue and digital inputs, the sister Director Mk2 product is closer to what you want.
The Diamond DAC has a compact form factor (278x57x300mm, WxHxD) and weighs just 3.15 kg. Its pleasing chassis design has a neat brushed silver fascia, although black and red are also available. The volume control is a pleasure to use, and the input selector rotary encoder is suitably robust and reassuring. The remainder of the fascia comprises a clock source switch, an on/off toggle switch and an informative LC display showing the input source, clock source and rendered bitrate.
SPL has chosen AKM's high-end 'Velvet Sound' AK4490 chip for digital-to-analogue conversion purposes. The company's representative, Sascha Flocken, says: “We did many listening sessions with different DACs over the past years. In all tests, we preferred the AKM chips in combination with our VOLTAiR technology output stages. We try to hear and listen instead of only looking at specs. Most of us at SPL have a background in audio, as a musician, mixing or mastering engineer, so sound is really important to all of us.”
Thanks to the AKM chip, the Diamond DAC offers impressive number-crunching abilities. For USB, this means PCM audio up to 768kHz, and 11.2MHz (DSD256) for DSD (DSD over PCM DoP) audio signals. AES/EBU, S/PDIF and coaxial inputs support PCM up to 192kHz. During listening, a relay clicks when switching between input formats; although not obtrusive, this may bother some users in a headphone or near-field configuration.
Useful for those of us with external clocks, the clock source can be switched from the selected input source or an externally connected word clock. The DAC is calibrated to an output level of 15dBu at 0dBFS. To reach the limits of the DAC in a Windows-based computer audio configuration, SPL offers drivers for Windows 7 through Windows 11. For the same macOS or iOS connectivity, no device drivers are necessary.
SPL worked with an external developer on the board's design for the Diamond DAC. The company says: “In our experience the analogue implementation is the key to making digital sources sound 'high end'. A significant design feature of the Diamond DAC is the VOLTAiR technology that allows the DAC to offer ±60V DC rails to process analogue audio signals.”
This equates to 12dB more headroom in the signal path, and SPL claims this permits all components to operate continuously in their optimum operating range. Such an approach required innovation from SPL, creating proprietary operational amplifiers to handle the high DC voltages that would ordinarily fry conventional op-amps. The approach is said to deliver excellent measured performance (134.5dB dynamic range), and the higher operating voltage also positively impacts the distortion limit and signal-to-noise ratio within the device. A low pass filter must filter the analogue output of any DAC chip. There are two DLP120 filters in the Diamond DAC, one for PCM and one for DSD, since different roll-off frequencies are required.
With a straightforward control panel, intuitive connectivity, and logical controls, setting up the DAC is a breeze, showcasing its impeccable engineering. I streamed hi-res audio over USB from Qobuz using Roon to evaluate the SPL Diamond DAC in my system. The Diamond DAC acted as a preamplifier for my Barefoot Audio Micromain 27 active studio monitors.
From the moment you start using the SPL Audio Diamond DAC, its professional audio quality is evident. Modern electronic music sounds fantastic through it, benefiting from the latest production techniques to deliver a highly immersive listening experience. On more intimate recordings, the SPL lets the emotion flood through, while harsher, more straightforward rock comes across warts and all – in a satisfyingly tactile, visceral and earthy way. While it faithfully presents raw and unfiltered rock music, it never sounds abrasive. Older, well-recorded tracks feel refreshed, with the DAC revealing nuances that breathe new life into familiar songs.
The recent Róisín Murphy album Hit Parade is a real winner in this household. The album opener What Not To Do was produced with DJ Koze and is a great jumping point for the collaboration. It opens with sampled vocals, percussion and synths before the soaring vocals cut through the mix. Via the SPL DAC, bass was very accurate yet liquid, with a lovely roundness that reminded me of my trusty reference MSB Premier DAC. The full width of the stereo soundstage was used to perfection here, with this product ably demonstrating its pro audio pedigree. I could imagine Koze mixing this on gear not too dissimilar to this, such was the Diamond DAC's glass-clear sound.
Shellac's Steady As She Goes showcases the band's distinct minimalist and raw approach to rock. The track employs a stripped-back instrumentation, sharp angular guitar riffs, and a rhythm section that punches with both precision and power. The production is intentionally bare-bones, allowing for a gritty, almost confrontational audio experience. Steve Albini, the band's frontman and renowned audio engineer, is known for his analogue recording techniques, which give his songs an organic, tactile quality. Leveraging this meticulous recording approach, the Diamond DAC served up a vivid and expansive soundscape, allowing a deeper immersion into the band's unique sonic world. It made the track resonate with more intensity and authenticity than expected. Without adding obtrusive sibilance or other such distortion, the SPL DAC let me play this aggressive-sounding track at high volume levels in a satisfyingly fatigue-free way.
Indeed, the Diamond DAC has a wonderfully open and nuanced midband. Chan Marshall is known for her intimate songwriting and emotive production quality. On Wanderer, a hauntingly minimalistic musical approach is taken, with each instrument given abundant space to breathe, and her vocals exude a sense of vulnerability and raw emotion. The superb production emphasises the lifelike nature of her voice, putting the listener in a quiet room with the artist herself. The Diamond DAC ensured that the ambient nuances in Marshall's vocals were captured in their full, impassioned glory. Every breath, whisper, and vocal inflection was presented with clarity, the SPL capturing this lifelike nature of the track's production in all its glory. For example, her atmospheric vocals were rendered with eerie precision and complemented the backing vocals in a most beguiling way.
Diving into Runnin' Down A Dream from Tom Petty's seminal Full Moon Fever album is a vibrant journey through classic guitar rock's heart. The magic here lies in Jeff Lynne's production, which seamlessly melds raw energy with polished sophistication. In my home studio, I usually listen through a Presonus 16-channel digital mixer or a Matrix Audio Mini-I 3 Pro DAC. Neither of these devices is a slouch, but introducing the Diamond DAC to this mix was transformative – it was like enhancing a cinematic masterpiece with high-definition clarity. This track came alive in new ways. Every guitar strum, beat of the drum, and timbral resonance of Petty's voice appeared to be amplified and enriched.
Stereolab's Miss Modular weaves an intricate aural narrative, drawing upon a rich palette of analogue synthesisers, vibrant jangly guitar riffs, and hypnotic pulsing rhythms. The Diamond DAC elevated this listening experience to another dimension. Acting as the virtuoso conductor of this symphony, it revealed this excellent recording in its full glory. Such impeccable precision made for superb instrumental texture – each sonic element gleamed – further adding to the track's distinctive retro-futuristic ambience. This little digital-to-analogue converter unfolded the track's layered magnificence in a wonderfully satisfying way.
Overall, this little DAC delivers exceptional accuracy without compromising on the natural warmth and richness of a recording. It offers abundant headroom, ensuring clarity even in the most dynamic of tracks or when pushing your system to the limits. Listeners can expect a non-fatiguing auditory experience, making this DAC perfect for extended sessions. The soundstage is expansive, positioning instruments and vocals distinctly within a three-dimensional space, adding depth to music. Furthermore, this DAC shines in its ability to clearly separate and present intricate layers within complex compositions, making them accessible and enjoyable for listeners.
SPL's Diamond DAC is an unashamedly traditional digital-to-analogue converter with solid professional audio DNA. It has a relatively minimalist user interface, excellent connectivity, and an extremely capable audio core based around a highly regarded proprietary DAC chip. The analogue output stage is very well-engineered, too. The result is a superb-sounding product with forensic detail retrieval capabilities but with a smooth and natural tonality. Highly transparent, very dynamic and an excellent communicator on an emotional level, it makes music magic.
As such, this product is a serious challenger to considerably more expensive DACs – and food for thought for the latest product releases from PS Audio and other contemporary market rivals. The benefits of decades of pro-audio engineering prowess are clearly displayed here, so people searching for their endgame DAC would do well to audition it. This isn't for everyone – fans of built-in streamers and other such luxuries should look elsewhere – but it perfectly hits the spot for purist audiophiles.
With an engineering degree in digital signal processing and a storied career in IT networking and cyber security, Craig loves to push the boundaries of audio technologies. An aficionado of live music with personal detours in music production and event promotion, Craig is a long time enthusiast of post punk, electronic and experimental music.
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