KingRex HQ-1
Headphone Amplifier

Pound for pound, it is impossible to match headphone fidelity with regular loudspeakers. Once you've been intimate with a track via the ultimate low-distortion, high-resolution playback medium, without colouration or room interaction, the bar is irreversibly raised on your expectations of its reproduction over loudpeakers.

The all-new KingRex HQ1 Headphone Amplifier (codenamed Headquarters) is a two-box design, with a linear 18V / 1.25A power supply developed from the proven KingRex PSU: a 48VA toroid, with five 2.200uF caps filtering incoming AC, three 4.700uF units smoothing outgoing DC. Eight "hifi-grade Nippon Chemicon electrolytics" create a total power supply capacitance of 25.100uF.

The circuit is classic class A with Mosfet outputs—Toshiba A970/C2240 transistor for first stage, Hitachi 2SK214 for the current buffer. Power consumption remains below 10 watts. At 2Vrms output, THD+N is 0.005%. Dynamic range is 110dB, channel separation >92dB at 1kHz and >76dB at 10kHz and S/N ratio 115dB. Circuit gain is 18.5dB, making it a standard medium gain one-source preamplifier if so used. I/o impedances are 15K and 1.8 ohm respectively, frequency response is 20Hz (-0.7dB) to 80kHz (+0.1dB).

6 Moons recently conducted a four-way group test pitting the KingRex HQ1 against three of their favourite headphone amplifiers: the Yamamoto H-02, the Trafomatic Head One, and a $4000 Woo Audio Model 5 fitted with EAT 300B Triodes. Extracts follow:

“Texturally leaner by way of the KingRex did not mean cooler. Rather, it only meant crisper, with less stuff around or between the notes. Tonally, the Headquarters was not thinner or flatter. The matter was about textures, about what's apparently on the surface of notes. Second-order tube harmonics only created micro fuzz like fine suede. The KingRex was smooth polished leather instead.
    The KingRex proved most conducive to the more extreme scenarios of 'wide' cross feed (speakers) allied to max amplitude and max delay times. The greater subtle fuzziness of the Yamamoto and Woo became more echo-y and resonant.
    As complexity of recorded material increased, the KingRex and Trafomatic had the separation advantage. That could keep greater numbers of performers discrete rather than begin to bleed together. This also related directly to the amount and degree of cross feed they could tolerate. I could follow Dino Saluzzi and Anja Lechner [Ojos Negros, ECM] over the KingRex without any perceived loss of tone and admire their burnished cello and glittering bandoneon uncut.
    The built-in low noise floor of the HQ-1 serves it very well as a big-system preamplifier indeed . . . . Small boxes, big heart.
   In conclusion, the two-box Headquarters majors on the kind of unforced natural resolution superior noise floors and non-stressed class A-biased output devices often arrive at. While the transistor virtues of cleanly rendered transients are evident, they aren't overstressed. Tone weight is higher than expected.
   It's clear that KingRex has a winner on their hands that's mature out of the gate. The amp isn't warm per se but does have a tone density that's indeed very similar to what we know from tubes. The HQ-1 focuses on articulation, definition and crispness with great solidity of tone. While costlier than the company's initial offerings, KingRex fully delivers the higher standards which the new sticker would demand. KingRex now plays in the bigger leagues. Welcome to da club!” – 6 Moons

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