The brand new WestminsterLab Quest solid-state preamplifier has just arrived at Mono and Stereo and is undergoing a review. This is the full version with the extended carbon fibre package installed. After the extremely positive debut of WestminsterLab electronics with REI class A power amplifiers, the Quest follows the same uncompromising path.

Here is the breakdown of all the important features and what makes the WestminsterLab Quest very different from the beginning.


The ultimate aim of the Quest is to create the perfect preamplifier to accompany the Rei and the cables lineup. With the Quest, WestminsterLab completes the complete high-end audio loom between the source and pair of speakers. Setting out to push the boundary, it redefines how a preamplifier can contribute to the system and the ability to extract every bit of potential from both the recorded music and the music reproduction system.


During the inception of the project, the WestminsterLab team endlessly question the role of the preamplifier in an audio system and constantly challenge whether a preamplifier is absolutely necessary for a system and what qualities the added stage can bring or may bring to the outcome. They've begun with a fresh start to investigate the relationship between the source and the amplifier. Every section of the preamplifier has been looked at thoroughly to see how every single part could be improved and also what kind of synergy can be extracted from each and every part.


Not all experience that was gained from developing UNUM and Rei could be transferred to the Quest. As High Current & High Voltage signals behave very differently to Small Current and Low Voltage signals which the Quest handles. Everything has to basically start from scratch from how the signal is handled, the route it goes through, the types and materials of resistors and transistors, etc. It is a completely fresh start from the ground up.


For both Rei and UNUM amplifiers are a fully balanced design, it is obvious that WestminsterLab prefers balanced architecture and surely the Quest is featuring full balanced architecture. For the Quest preamp, WestminsterLab has taken this concept even further by using a rarely adapted dual-mono full balanced design. 

From the input selection relay, input circuitry, volume control all the way to the output driver circuitry, both left, and right channels are completely isolated, bringing an exceptional channel separation to the Quest to preserve the finest and most delicate musical information.


The power supply of the Quest provides the fundamentals to the extraordinary musical performance. With 10 separate power rails, they provide the highest possible separation between different channels and for different parts and modules within the unit,

Different rails are designed specifically to the needs of different sections of the particular part due to the varied needs and conditions, ensuring ultra low noise performance to deliver the micro dynamics and details within the music. An extra and separate transformer and power supply are dedicated to the non-audio section. In some parts, 2-stage linear regulation is adapted to exert more control on the regulation for some ultra-sensitive components within the Quest.

The O type transformer used in the Quest provides even higher efficiency than usual toroidal and a cleaner, purer, faster power due to its different iron core design.


Signal attenuation is one of the main functions of a typical preamplifier. There are many different ways to attenuate the signal - optical coupler, autotransformer, resistor ladder, etc, and each of these solutions has its ups and downs and may heavily impact the behavior and quality of the sound.

After extensive listening test and lab analysis, Leung and his team have chosen a shunt type stepped resistor network solution. The 4 channels of 64 steps precision resister network and ultra-low noise relays have their own dedicated power regulator and power supply. WestminsterLab engineers have also kept the control logic as minimal as possible, an LED display with remote control function only. It further minimizes any possibility of interference.


The overall ground design and grounding scheme can hold a significant impact on the overall performance of the system, especially for tiny signals like the Quest handles. Tremendous effort has been put to design the grounding of the Quest and a new grounding scheme - Hybrid Grounding was developed. Hybrid Grounding allows users to switch between two grounding modes on the fly to configure their Quest specifically for their system and look at the grounding scheme as a whole.


WestminsterLab has gone to the end of the world and taken extensive measures to protect the fragile signals going through the Quest. Metal absorbs radio interferences from the environment and these interferences then convert to electrical noise and magnetic disturbance which affect the whole system.

Therefore, extensive use of carbon fiber as shielding materials was adopted inside out, instead of the usual copper or aluminum braids and foils, which does not generate any magnetic fields and unwanted eddy current, and amazingly in return, it rejects interferences without absorption in nature. It also provides very high stability over environmental changes and extreme rigidity which gives low resonance and vibrations.

Furthermore, many signal handling relays in the Quest feature a soft start mechanism, different sections within the unit are isolated and compartmented, making sure that the cross-interference is minimized.

For customers who want the best of the best, they

can choose to purchase the extended carbon fiber option which adds another layer and barrier of carbon fiber shielding inside the unit.


At the back of the unit, there are two slots where users can insert expansion modules in the future. These sockets are designed to provide flexibility to design modules to add more input functions to the unit. For now, there is an RCA input card, and in the future, there may be a phono input card or even a digital input model.


By reducing unnecessary components and simplifying the schematic another advantage in the flexibility in designing the layout of the PCB was gained. This flexibility enabled WestminsterLab to design the layout to minimize the interference between signals and power supplies. If possible, signals often run perpendicularly to each other, even if not, they would run as further away from each other as possible to reduce unwanted interferences.


The ethos behind the industrial and electronic design of the Quest echos with the WestminsterLab tradition. 

Keeping unnecessary features and ornaments to the minimum brings the purest musical and user experience to your living room. No fancy color display, UV meter, or any distracting items. Prepare to rediscover your music.


I am sure you got a good idea of how much time went into the production of the WestminsterLab Quest preamplifier. The REI Class A power amplifiers have shown how seriously Angus and the WestminsterLab team take their products, and Quest not only builds on these foundations, but continues to explore the universe of micro amplification with its proprietary, fully balanced topology, and extremely refined operation. 

Stay tuned for the second part and the final review, in which I will summarise my conclusions and point out special qualities of Quest with musical references.

Matej Isak


  • 22.000 USD 
  • optional extended carbon pack


  • Distortion: less than 0.0001% @ 1kHz
  • ​Signal-to-Noise Ratio: more than 120dB, unweighted 
  • Input: 3 sets of balanced XLR input, 2 optional modules
  • ​Input Impedance: 51 kΩ​
  • Input Voltage: 6Vrms
  • Frequency Response: 2Hz to 100kHz, 0.1dB
  • Outputs: 2 sets of balanced XLR outputs
  • Output Voltage: 12Vrms
  • Channel Separation: more than 120dB
  • ​Gain: 6.5dB
  • ​Volume Control Range: 0 to -63dB / Mute
  • ​Dimensions: W470 x H110 x D392 mm
  • ​Weight: 13.2KG


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