KingRex PreAmp

KingRex PreAmp

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.

Key components include three pairs of Burr-Brown IC: OPA627 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, 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.


(1) The Pre-Amp us designed to use two sources. Each source is selected automatically depending on which is outputing the signal. Switching is carried out via a high quality relay. When using two sources ensure that the one not being used is muted or turned off.

(2) Pre-Amp uses a low noise FET input OP-AMP. The highly-regarded and expensive OPA627 is used as the main OP-AMP, with a BUF634 increasing the current output. The addition of a DC servo circuit enables the elimination of sound degrading coupling capacitors, resulting in a purer and more accurate representation of the original source.

(3) A built-in 'diamond buffer' stage is added at the input to increase the dynamic range of Pre-Amp.

(4) High quality gold-anodized phono input and output sockets are used.

(5) To encourage the owner to experiment with his/her preferred sound, we have designed the Pre-Amp with socketed OP-AMPs. This allows the user to change the OP-AMPs as/when new and better units become available.

(6) All this technology – including a dedicated torroidal transformer and regulator circuitry for the PSU – is housed in a tiny and smart looking case.

Pre Amp Circuit Path

PreAmp Rear Panel

RRP: £290 (inc VAT)


180 x 140 x 45mm

Weight: 2.1kg


To place an order in the UK or EU, send us an email or visit Item Audio >