For those vinyl fans who wish to discover and experiment with the advantages of processing needle-drops in the digital domain, the Groove Sleuth MICRO is our entry-level, non-equalising preamplifier.

The only major limitation of the Groove Sleuth MICRO is that it may not include internal RIAA equalisation for monitoring which may be included in the Groove Sleuth Mk. II and the Groove Sleuth Lockdown preamplifier.

The diminutive Groove Sleuth MICRO preamplifier is suitable for all moving-magnet cartridges or for Phaedrus Audio PHLUX II active moving-magnet cartridges (add the GS-MICRO-PHLUX OPT order option).

For operation with low-output, moving-coil cartridges, we have the partnering Groove Sleuth TRANSFORMER.

Like the Groove Sleuth Mk. II and our flagship Groove Sleuth LOCKDOWN preamplifiers, the Groove Sleuth MICRO preamplifier incorporates the very low-noise battery supply. This means the preamplifier can be powered from a conventional, international-style power supply but be switched to battery supply during operation to ensure the very best possible noise and distortion performance.

This delivers first-rate quality at a very reasonable price. A switch on the front-panel allows the battery supply to be selected. The Groove Sleuth MICRO preamplifier has over 4 days operational charge, but we recommend battery play be limited to approximately 12 hours. The unit may be kept in charge mode when listening with only a minute loss of quality.

It was ...... more specific across the mid-band. clean in treble.....
   It wasn't the LP as I know it. Noel Keywood (review of Stereo Lab)

Computer audio

The Groove Sleuth MICRO preamplifier permits connection of turntables to a computer sound-cards for use with powerful digital audio tools like Pspatial Audio's Stereo Lab software.

For the vinyl enthusiast, Stereo Lab offers a suite of tools for capturing the highest quality needle-drops from both modern, LP records. It also incorporates sophisticated, best-in-class noise-reduction and distortion-reduction tools and decoding of all historical quadraphonic formats: QS; SQ; Ambisonics UHJ; carrier CD-4; and others.

And, for the record collector and sound archivist, Stereo Lab also includes a Historic Equalisation mode which implements a comprehensive collection of gramophone-record equalisation curves; enabling the correct de-emphasis of 33, 45 and 78 RPM recordings made from 1880 to today!


All Groove Sleuth preamplifiers feature the iLOOP; a wide-bandwidth, low-noise and distortion buffered loop-through.

Groove Sleuth MICRO PHLUX-Bridge version

The cut-down version Groove Sleuth MICRO preamplifier (PHLUX-Bridge version) allows the PHLUX-II active phono cartridge to be used in all standard hi-fi applications as the base-station for the PHLUX-II active cartridge.

Sitting between the cartridge and the preamp', the Groove Sleuth MICRO PHLUX-Bridge version supplies power to the cartridge and forwards the cartridge signal (via Phaedrus Audio's unique iLOOP signal-path) to the phono-preamplifier or integrated amplifier. The LINE OUT is inoperative in the PHLUX-Bridge version and is not present.

The Groove Sleuth MICRO manual - which includes the manual for the Groove Sleuth TRANSFORMER is here.

Brief video introducing Phædrus Audio's tools for moving-coil cartridges


Housed in the same diminutive chassis as the Groove Sleuth MICRO preamplifier, the Groove Sleuth TRANSFORMER includes a pair of high-quality step-up transformers to extend the range of the Groove Sleuth MICRO, or any other standard MM preamplifier to include all moving-coil and moving-iron cartridges.

By incorporating a range of transformer ratios (fitted as a time-of-order option), the Groove Sleuth TRANSFORMER can adapt to the entire range of modern, moving-coil cartridges: from exotic, low output devices to "high-output" moving-coils, like the Denon DL-110 which rather "under-load" standard MM input stages without a transformer. Here is our guide for which Groove Sleuth TRANSFORMER to select according to your cartridge.

The high-quality transformers in the Groove Sleuth TRANSFORMER have cores of high permeability, nickel-iron alloy and incorporate a Faraday shield between primary and secondary to keep out radio-frequency garbage. The transformers are fitted in tight-fitting mu-metal cans and are thus magnetically screened. The large primary inductance of the transformers ensures an extended low-frequency response.

Groove Sleuth TRANSFORMER - Signal level management

TRANSFORMER 1 has a step-up ratio sufficient for the lowest output, moving-coil cartridges.

TRANSFORMER 2 is an exceptional quality device which covers MC cartridges which prefer a slightly higher load.

TRANSFORMER 3 is intended for "high-output" moving-coil cartridges which could do with a little more level into a standard MM phono input.

Here is our guide for which Groove Sleuth TRANSFORMER to select according to your cartridge.

If your cartridge is not on this list, please contact for further advice.

The transformers in the TRANSFORMER product have a frequency response in the 15kHz to 45kHz range which is good enough to be "first-class" as judged by JVC's CD-4 frequency response criteria.¹

This means the TRANSFORMER may be used to needle-drop CD-4 records with a suitable wideband moving-coil cartridge (fitted with a Shibata or similar stylus).

1. Technical Requirements and Analysis of Phono Cartridges for Proper Playback of CD-4 Discrete Four-Channel Records T. INOUE, N. SHIBATA, AND K. GOH JAES APRIL 1973, VOLUME 21, NUMBER 3].

Groove Sleuth MICRO preamplifier - Key features and specification

† Not available in PHLUX-Bridge version

Groove Sleuth TRANSFORMER (1)

Phædrus Audio reserves the right to change specification without notice.


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