"There are no cartridge loading options on this Reference. I built this for my own use and really don't like any switches on the very low signal coming from a low-output moving coil cartridge. It is loaded with 1000Ω, a value that should suit any well-engineered cartridge. It may be contentious but I believe any cartridge that needs a low or particular loading value isn't that good a cartridge. The phono stage is very quiet, probably as quiet as a tube moving coil phono can be. With some systems it may be necessary to turn the volume past 12 o'clock or even further, maybe to 3 or 4 o'clock. Please note that this makes no difference to the performance. The volume control simply attenuates the output. Even at full volume the output is clean and distortion free." That was a synoptic summary of Mick’s views and philosophy when it comes to preamplifier design. I remember Mick telling me why he has built so many different preamps—in the main but not exclusively—"because in my opinion they are the heart of the system." I for one emphatically agree. And I’d go as far as adding that the preamplifier is also the soul of the system.


Directly written words. As Maloney mentioned, DHT preamps are rare in that a circuit suitable for modern expectations is difficult to implement due to inherent noise/microphony issues. For the purposes of this review, I had two units on hand, one of which is my own for the reference system. One was extraordinarily quiet in low gain mode and in fact as quiet as a valve component can possibly be. It exhibited very low-level hum at high gain. Fortuitously this was my own unit. The second unit was marginally noisier in the low gain setting while in high gain it exhibited hum and buzz which were audible from the listening position. It should be noted that my reference Halo JC 1 monos have 29dB of voltage gain whilst Wilson’s Alexia are fairly efficient at 91dB. The very common 26dB gain amplifiers and speakers of 87dB to 89dB sensitivity would alleviate any noise issues further.


The Reference DHT offers a number of unmarked (!) connectivity and functionality options but the owner's manual of course explains everything. There are a single XLR and three RCA line-level inputs selectable by switch; an RCA phono input; and no less than three RCA outputs with a single XLR out. A grounding post is provided for the phono stage. Towards the rear of the top panel is a switch to select output via transformer or capacitor coupling. The central position switches to mute. Further switching is provided via a small toggle on the top panel’s front right for input transformer on/off (the transformer input should not be used with sources with >1’000Ω impedance and of course it’s not to be used with the phono input). A small rotary knob acts as balance control.


The preamplifier features 2 x 4P1L (signal), 2 x 6H8C/6SN7 (phono) and 2 x E180F input valves. In the power supply are one 5AR4 rectifier and two 6L6 regulators. A twin set of umbilicals—one each for the line and phono stages—mate power supply to the head unit. For the IEC socket with incorporated fuse, Supratek recommends a 3.15A to 5A slow blow fuse replacement (spare fuse is included). Specifications are provided in basic form and include a frequency response of "far better than 20Hz to 20kHz at 0dB", an output impedance of around 200Ω transformer coupled and approximately 1'000Ω capacitor coupled. Input impedance is 50KΩ. Voltage gain varies between 6dB transformer coupled and 16dB capacitor coupled. Further minor gain adjustments can be made via the transformer input option. Aesthetically and to this writer, there’s very little that competes with the glass, metal, chrome and wood of Supratek preamps. They are somewhat art deco by design. Whilst the build quality is not a patch on Boulder or D’Agostino standards for example (but neither is pricing by a long shot), the chassis assembly is tidy and the unit certainly has a wow factor for elegance of design.


The hot sound of directness. Many experienced audiophiles suggest that the Holy Grail of preamplification is the directl-heated triode circuit. Even a basic DHT, if there is such a thing, promises a directness and openness which other circuits would struggle to match. But its claimed Achilles heel is the bass range where some have experienced bloat and ill definition. This issue I’d like to tackle from the onset. The Supratek Reference DHT provided a bass range commensurate with the very best preamplifiers I have ever reviewed, be they valve or solid state. In my system this manifested as a visceral attack that punched the gut whilst providing accurate levels of detail and tonal textures. Simply put and without overemphasis, the entire low end was impeccably reproduced. There, myth busted!