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KingRex Pre-Amp

KingRex' Pre-Amp is a hybrid design that improves on conventional voltage amplifiers with discrete components and high-performance op amps, mated to a smart auto-select line input facility. It features the same aluminum faceplate, volume knob and chassis measurement as its PSU and T20U siblings. Although it has been designed, visually and sonically, for compatibility with the T20U, the Pre-Amp has proven to be a great match with a wide variety of valve and solid state power amplifiers, exceeding the performance of components many times more expensive. It also benefits from being one of the most energy-efficient active pre amplifiers available.

Key components include Burr-Brown OPA627 op-amps for pre-amplification (a new generation FET (Difet) op amp recognised for its low noise and high speed), BUF634 for increasing and sustaining higher output current (BUF634 is not only a high speed op amp current booster, it also improves compatibility with power amp and loudspeakers), and OPA177 for DC servo, ensuring the op amp output is free of DC power, avoiding any chances of harming the power amp and the loudspeakers. It also has another advantage: it negates the need for extra output coupling capacitors.

On the power supply front, the KingRex Pre-Amp is equipped with an 8VA toroidal transformer and a pair of National LM317T voltage regulators, delivering 13V/0.3A DC current to the circuit board. The secret weapon is the unique design: plug-in PCB, Diamond Buffer circuit, which is a transistor-based all discrete-component buffering circuit that fine-tunes the incoming audio signal for frequency extension, tonal accuracy, holographic imaging and warm, tube-like atmospheric effects. The Diamond buffer PCB is mounted on top of the lower-deck main board through multi-pin (detachable) connection.

The Pre-Amp monitors and intelligently auto-selects between two line sources. Switching is carried out via a high quality relay. High quality gold-anodized phono input and output sockets are used and the beautifully compact housing is machined from aluminium.

“As with the power amp this is a little jewel. Think micro 'Cello' meets Lab 47 and you'll get the idea. The machined volume knob was silky smooth, beautifully finished casework, good quality binding posts etc etc. I've always been a fan of active pre-amps and the KingRex Pre-Amp just showed what a really good pre-amp can do . . . the Pre-Amp could have fooled me into thinking I was listening to a really pricey valve amp (and you know I'm a valve user), maybe not a mega-buck SE, but one of the better PP's and very like a 300b PP I had here a while back that cost 20 times as much.

Conclusion: I hopelessly underestimated the KingRex Pre-Amp. In partnership with the T20 it delivers on the promise made three years ago by the original T-amp, true high-end sound for real-world money. If I were allowed to award a personal 'component of the year' this would probably get it (it's only June after all...). For the money it's almost impossible to fault, in a money-no-object situation it can still make a strong case for itself, not least because of the convenience. – TNT Audio, 2008

“The T20U alone . . . was confined to small-scale home audio parameters yet scoring high on most sonic attributes. Now with the Preamp and two T20U bi-amping four speakers, its real potential was unleashed. Every sonic attribute was augmented to a new level. Scale and dimension were elevated to concert hall presence, musicality to connoisseur grade. The only thing I could criticize was the bottom octave. So I took the trouble of moving the Klipsch Synergy F2 down to remedy the situation. My diagnosis proved correct. The amps could reach the bottom octave without the slightest sign of stress or fatigue. The F2 synergized perfectly with this KingRex pre/power combo and the whole shebang was so close to a tube experience. If the F2 is indeed made for tube amps, then the KingRex combo is made to emulate tube amps. Unrestrained valve bloom released freely in the air. Musicality lingered on and on yet layering and definition were not compromised.

I threw in another CD, Roby Lakatos and his ensemble's yellow label debut recording Lakatos [DGG 475 879-2]. Hungarian Gypsy passion filled up the room. High and low vibrations of the strings riding on the resonance of soundboards big and small, curved and square, they all radiated through the musicians' body heat. I secretly noted down: "Who needs tube amps?" Not if you heard the kind of rhythmic pulse and forefront transients of strumming fingernails on acoustic guitar, deftly wooden hammers flying across the cimbalom and lightning-fast pizzicato fingertips on the violins that all added up to the heart-throbbing reality I just witnessed. If I may say so, there's one advantage of this KingRex combo over your entry-level tube pre/power combo, which almost certainly will cost more: the KingRex is more capable of adding verisimilitude to every musical plot and with more attention to inner details.

The other preamp I like to use occasionally in this setup when I really need more SPL and valve bloom (for Mahler Symphonies and Richard Strauss tone poems for instance) is the Dared SL-2000A, which has a high 26dB of gain. With the KingRex Pre-Amp I got about the same warmth and valve bloom with perhaps a bit more natural decay. But the soundstage was definitely wider and that's so much better for Mahler. When I dialed up the volume to 12 o'clock, the sound pressure felt like a body massage yet musicality was still impeccably well mannered.

When matched with high-power class-D amps, it offers unbelievable value and uncompromised performance. Its possible applications go on and on. On the last few days of auditioning, I even used it to substitute a $2,000+ tube preamp in an all-tube preamp/monoblocks setup and honestly preferred the KingRex for its much quieter background noise, wider tonal spectrum and logical balance of musicality and resolution. I know it might seem unscrupulous on my part to give out second and third Blue Moon Awards to KingRex within just two consecutive reviews. But I could not possibly deny them this well-deserved honor: the T20U for "The tube-sounding USB Tripath amp" and the Pre-Amp for "The best compact preamp embodying value and performance." – 6 Mooons Blue Moon Award Winner

“The KingRex preamplifier is a bit of an enigma. After all, why would an integrated amplifier need a preamp? Once the music starts to play, questions like this simply become irrelevant. While the preamplifier adds another level of gain, I believe the Diamond Buffer Circuit is primarily responsible for the improvements in sound quality.

Virtually every aspect of the music improved once the KingRex preamplifier is combined with the two other components [T20U and PSU]. Replaying "Justice" clearly shows the benefits of adding the preamplifier, and these were not subtle improvements. Low-level detail retrieval is improved, and the contrast between instruments becomes easier to hear. The micro-dynamic presentation of the music improves, and the contrast between instruments is heightened. The soundstage snaps into focus, and performers are clearly delineated. Finally, high frequency extension is significantly increased, to the point where the T-20 could now be mistaken for a different amplifier. Ambient information in the song is easier to discern, and the decay of notes have a natural feel to them. The KingRex preamplifier completes the transformation of the humble T-20 amplifier, and the end result is an authentic high performance amplifier with an affordable price tag.

Even for those with the slimmest of budgets, the T-20 integrated amplifier offers above average sound quality. For those with a few more dollars in their audio kitty, the PSU linear power supply is a cost effective upgrade that deals with a couple of limitations brought about by the switching power supply. The KingRex preamp is the real show stealer, and anyone who appreciates high quality electronics is going to recognize the merits of this trio of components. ” – Positive Feedback Issue 46

KingRex Pre-Amp Rear Panel

KingRex Pre-Amp Rear Panel

  • 12dB gain active line level preamp
  • 2x auto-switching RCA inputs
  • Single set of RCA outputs
  • Frequency response: 20Hz–20kHz
  • Noise level: -104.6dB (A)
  • Dynamic range: 104.5dB
  • Total harmonic distortion: < 0.0047%
  • Power consumption: 3W idle
  • Size: 180 x 140 x 45mm
  • Weight: 2.1kg
  • IEC socket
  • Comes with UK power lead
  • 12 month UK warranty

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