SPL Phonitor X Headphone Amplifier

Power Galore

Equipment report
Solid-state preamplifiers,
SPL Phonitor X
SPL Phonitor X Headphone Amplifier

Ergonomics and Setup
Compared to some high-end audio gear that sports a “super-luxury finish” the Phonitor X cosmetics are more about function than bling. The front panel has a large, centrally located volume control flanked on the left by analog and digital source selector switches, an output selector switch, crossfeed angle control, crossfeed switch, and the matrix on/off switch. On the right side of the volume control is a pair of input level VU meters, balanced and single-ended headphone connections, and an on/off switch. The front panel itself is about ¼-inch thick and is available in silver, black, or red. My review sample was the red version, which looks lovely, though its mid-tone color makes reading the dark silver lettering exceedingly difficult for my well-worn eyes, especially in low light. I spent the first week of use with the owner’s manual on my desk, turned to the page with pictures of the front panel so I could see (and memorize) the control’s labels.

The back panel of the Phonitor X includes one pair of balanced and unbalanced analog outputs and one pair of balanced and unbalanced inputs. If your Phonitor has the optional digital interface it will also have a coaxial SPDIF, TosLink, and USB input. The back panel also has a pair of trigger controls to activate other SPL products, and an IR PGM that allows you to pair the Phonitor X with any remote control. Finally, the back panel contains an IEC AC connection and a power on/off switch.

The Phonitor X includes crossfeed and matrix circuitry. The Phonitor X is certainly not unique among SPL headphone amplifiers in this respect. The Phonitor X has fewer adjustable options than the Phonitor II, but it does have more choices than most other manufacturers’ headphone amplifiers, which usually have just on and off. The Phonitor X has four speaker angles 22°, 30°, 40°, and 55°, and five different crossfeed levels.

I used the Phonitor X as a headphone amplifier and as a preamplifier. Its primary input was from the Mytek Brooklyn’s balanced analog output. This allowed me to send the Mytek’s unbalanced output to another headphone amplifier so I could do matched-level A/B listening tests between them. I tried using the bypass setting on the Mytek’s volume controls to send an unattenuated line-level output signal to the Phonitor X, but it was slightly too high a level and clipped the Phonitor X’s VU meters. Fortunately, the Phonitor X has a switch that calibrates the meters so that 0VU is +12dB. I listened to both the analog and digital volume controls set at ­­-9dB, and settled on digital volume attenuation as the most sonically transparent solution.

After the first ten days of use, I began to appreciate the Phonitor X’s ergonomic excellence and started using it primarily by feel. The large central volume control is easy to find, and from there, depending on what function you wish to adjust, you can find your way to every knob and switch without looking. SPL’s experience in making pro gear is probably the main reason the controls are so logical and easy to use.

On some devices VU meters are more for show than for practical use, but the meters on the Phonitor X have utilitarian value. First, whenever the Phonitor X is in mute mode they turn red, which makes it easy to tell if signal is really being passed through the Phonitor X to your headphones or power amplifiers. Secondly, since the VU meters measure the input levels, you can see if an input signal’s level is too low or high at a glance. Finally, the VU meters point up one potential problem with the Phonitor X: If the input levels are too high or low, you will need to alter them before they are routed to the Phonitor X because the unit itself has no way to attenuate input levels. The Phonitor has adjustable output levels, but it has no adjustments for input.

Unlike many high-gain or high-output headphone amplifiers, which have adjustable gain settings, the Phonitor X has no way to compensate for extremely high-sensitivity or low-sensitivity headphones. Given that the Phonitor not only has that 120-volt rail but also the option for an additional 12 or 22dB of gain, it’s hard to imagine that there are any “difficult to drive” headphones that the Phonitor X can’t power successfully. With my least efficient headphones, a pair of Beyerdynamic DT 990 600-ohm version, the Phonitor volume control barely edged past midway on my lower-output live concert and field recordings, without the need for any additional output boost from the dipswitches. With my most sensitive in-ear monitors, the Empire Ears Zeus (115dB sensitivity), there was noticeable hiss and some low-level hum and noise. So, if the vast majority of your listening is through sensitive in-ear monitors, the Phonitor X would not be your best option. That is not surprising given that in my experience very few headphone amplifiers have the ability to drive both sensitive in-ear monitors and inefficient large-diaphragm over-ears with equal efficacy.

Three headphones spent the most time tethered to the SPL Phonitor X: the new Focal Utopia, the MrSpeakers Ether C, and the Audio Technica ATH-W3000ANV. Both the Utopia and Ether C were attached using Moon Audio’s Silver Dragon cable with balanced terminations, while the ATH-W3000ANV was connected via its permanently attached, single-ended connection.

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