Issue 93


Ableton Live 12
What’s in. What’s out. What to expect.


Review: SPL Phonitor One d

An all-analogue unit, with the means to make your headphones sound like studio monitors, and 32-bit/768kHz conversion? I’m listening.


23 March 2021

“Jeeves! Fetch my planar magnetic HyperDrivers.” Setting down my pipe, I plumb them into the tungsten-lit, steam-belching monster that is my headphone amp and affix them to my ears.

“Put on the Kind of Blue original pressing… there’s a good chap.”

Entering audio nirvana, ascending to the third level of the astral plane, for a moment I reflect on the lowliness of the ‘have-nots’ with their M50s, K92s, DT770s and HD25s.


I splutter in half-amused disgust. The splutter soon turns from a scoff to a choke. I sniff my handkerchief. Ah yes. Snake oil.


To set the (1959, Columbia) record straight, I’m no audiophile. I appreciate good audio design but in the end, for me, it’s about results — are my mixes sounding better?

What I do know: Phonitor One d is the middle child in a family of similar devices, aimed at offering SPL-grade monitoring [Ed: ‘phonitoring’] and recording in more affordable packages, with super hi-res 32-bit/768kHz conversion. Slightly more obscure is the studio use for this. Unless you have inputs of equal resolution and/or a computer capable of rendering audio that detailed (my Ryzen 5 machine wasn’t keen on 384kHz, let alone 768k), 192kHz is about as high as may need to go. That said, reaching into your deep pockets for a pipe and $40 to drop on a beautifully recorded, DSD/DXD format symphony is a pleasurable experience, and a significant part of the value proposition when reaching for the Phonitor One d over its non-d little brother, which lacks the super-charged DAC chip.


Those familiar with the SPL brand may well be familiar with the Phonitor concept.

The original Phonitor product was a very 2008-looking desktop amp with conspicuous VUs — not to mention a characteristically clean and powerful headphone signal augmented by the novel Phonitor system. The key concept behind Phonitor: headphone mixes don’t translate well. SPL’s solution is to build an analogue circuit (no DSP trickery here) that feeds a little bit of right channel into the left can, and vice versa, just as you’d hear in a control room sweet spot. Rounding out the controls are ‘Speaker Angle’, time delay of the crossfed signal, and ‘Centre Level’, allowing the user to tailor their experience. Overall, this fixes issues such as bass translation and stereo imaging when moving over to studio monitors.

All the essential boxes above are ticked on the Phonitor One d: the ‘Crossfeed’ knob (speaker angle and centre level are fixed though) and a powerful and beautiful-sounding amp. It drives my 250-ohm Beyerdynamic DT1770 Pros really nicely, with an abundance of volume, along with a deep and wide soundstage.

In mixing an EP using the One d, ‘reassurance’ is the main word that springs to mind. In making mix decisions, especially those related to stereo image and space, I could be quite confident I wasn’t being sucked into filling my phones’ unrealistically wide panorama.

One example was a vocal piece I arranged and mixed, using a voice synth to fill out harmonic and sonic space in the mix. Without Phonitor, I likely would have left this element quite narrow, but turning the Crossfeed up to max and hearing the mix through the the equivalent of a ‘narrow’ pair of monitors, it was evident it needed to fill out the mix far more. Chorus, reverb and level attenuation squashed and stretched it into its rightful place, helping it translate well onto monitors and even my throw-around Bluetooth speaker.


SPL Phonitor One d
Headphone Monitoring Amplifier



    Link Audio: (03) 8373 4817 or

  • PROS

    Super-clean analogue amplification
    Phonitor Matrix actually helpful
    Crazy conversion for DSD playback

  • CONS

    Crazy conversion for DAW use


    Phonitor One d offers high-end headphone amplification without nudging into snake-oil greased audiophile territory. The Phonitor Matrix is a practical tool that helps your headphone mixes to translate. The DAC is ideal for some hi-res audio enjoyment on the side.


The Phonitor One d is clean cut, understated and powerful; truly a James Bond character. If this were true, the like of Waves Nx would be everybody’s favourite quartermaster, Q. Nx can place you at the helm of Abbey Road Studio A, with impulse responses and speaker modelling to emulate the mix environment. It’ll even track your head for realistic phasing.

The Phonitor One d doesn’t come close to this, but what it does offer is Phonitor tech, a clean analogue path (no DSP in the way) bolted onto an amazing-sounding amplifier with killer conversion. With a demanding pair of headphones and a taste for hi-res DSD/DXD audio, studio users will get most out of the One d as a dual-use monitoring controller and music enjoyment unit. 

Like many audio people, I’m increasingly relying on great headphones for critical listening and mixing. If you’re in the same situation or considering upgrading your monitoring with superior headphones, then you need to pay attention to what’s driving those headphones. The One d, for me, hits the sweet spot: it’s worth paying around A$1k for great headphone monitoring. Sure, you can pay more. But as you climb those heights you begin to enter the boutique realms of the over engineered and over hyped. Clear your throat into your handkerchief and I bet you’ll smell it too.


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  1. Hi Rob,
    Would you prefer the SPL Phonitor One d on top of the RME ADI 2 DAC if you had a Hifiman ARYA and about 1000 euro’s to spend?

    1. Hi Fonz,
      The SPL is certainly an option you could consider. The RME DAC and amp may well sound better for your money, and offer you a more HiFi-flavoured product. With your 1000 euro budget, you could go better, but the SPL is a great value product that could save you a lot of money!

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Issue 93


Ableton Live 12
What’s in. What’s out. What to expect.