Plinius Koru

By Michael Wong

December 2006

Plinius Koru phono preamplifier. $3250

Plinius Koru phono preamplifier (click for larger image)

Rear panel of the Koru (click for larger image)

Inside the Koru (click for larger image)

From their earliest days, a great sounding phono stage has been an integral part of a Plinius preamplifier. Classics like the original Plinius II, the Mark Levinson-esque mono preamplifiers, the 2.4 and M12 all featured fine sounding phono stages.

Phono duo

In 1996 Plinius released not one but two separate phono stages, the affordable Jarrah and the no-compromise M14. These preceded the new M16 preamplifier which was released as either a line input only preamplifier or with an onboard phono stage.

Together the Jarrah and M14 set the performance benchmarks for both affordable (sub-$1000) and expensive ($3000+) New Zealand made phono stages. This double act proved to be compatible with a wide range of amplifiers and continued largely unchanged for most of their impressive ten year production run. As testament to the Jarrah’s musicality, it is the phono stage owned by three AudioEnz writers, including yours truly.

And how better to test Plinius’ claim that the Koru is a worthy successor to the Jarrah than with the ménage a trois of phono stages I had on hand: Jarrah, M14 and Koru.

into the new

The Koru is the first model to feature substantial input from the new European distribution team. It uses a slimmed down version of the now familiar (and much admired) Ross Stevens curved design architecture. Dampening material is now applied to the lid, making it rattle-free. A sophisticated power supply and audio circuitry reside on the same chassis but are physically separated, reducing noise, electrical interference and lending the Koru a unique look.

The fascia is bare save for the Plinius logo and a blue status LED. Around the back is where all the action is.

The Jarrah’s slightly awkward to get to adjustments have evolved into a simplified set of DIP switches externally accessible on the rear panel. Separate banks of DIP switches for each channel have been replaced by a single bank for both channels. Four gain options; 50dB, 56dB, 60dB, 66dB offer greater user flexibility. Cartridge loading options have been reduced from the Jarrah’s bewildering 32 settings (did anyone really need such incremental loading e.g. 7.4, 7.5, 7.6, 7.7 ohms?). Now we have a much more sensible choice (22, 47, 100, 220, 1k, 22k, 47k), with two settings for capacitance, 100 or 570pF.

Good quality gold plated RCA’s are fitted for single-ended input and output duties. Although the circuit is not fully balanced, XLR’s allow for the use of balanced cables. A standard IEC socket and rear mounted mains switch are fitted.

Old and new

The Jarrah recreated music in big, bold strokes, full of dynamics and energy that made music fun to listen to. The M14 was even better, having a more sophisticated sound with greater detail, transparency, immediacy and awesome wall-bending bass.

The Koru doesn’t sound like these older models.

With the new physical aesthetic comes a new sonic aesthetic. Where the Jarrah and M14 drew the ear in with great rhythmic drive, underpinned by powerful bass (and a touch of bloom adding extra life), the Koru directs the listener away from the bass, towards the midrange and highs.

The sound of the Koru is very clean, emerging from a curtain of such pure inky blackness that the Jarrah’s silence appears slightly grey. The presentation is a little more forward, with greater dimensionality and immediacy, on a huge soundstage that expands well beyond the speaker’s boundaries. Transparency is quite remarkable, allowing the listener to see further into the recording. Tonally the Koru is seamless from top to bottom with a leaner, lighter touch than the slightly dark balance of it’s predecessors.

Dynamics are explosive with lightning fast transient response, an area where more modern phono stages were leaving the Jarrah behind. The Koru has a sense of absolute control over every aspect of music; the notes, the spaces between and the acoustic environment.
The extra transparency, neutrality and dynamics brings the Koru right up to almost-M14 levels of performance, leaving the Jarrah sounding a bit opaque and fuzzy.

Drawbacks are few and minor. Whilst the new found neutrality is appreciated, on occasion it can sound a little too calculating, slightly mechanical, a bit transistory in nature. The fast transient response concentrates on the initial impact, without fully developing the harmonic follow-up. Coupled with the afore mentioned coolness, the culmination is that the Koru is more mature sounding than the Jarrah without quite the same level of drive or sense of fun.

The final scorecard has the Koru excelling at most of the traditional audiophile benchmarks, missing out on just a little drive and fun, two areas where the Jarrah and especially the M14 hold a slim advantage. It’s overall performance surpasses the Jarrah and gets very close to the M14, at considerably lower cost.

While the Koru is much more expensive than the Jarrah, think of it as not as a direct replacement but as bridging the gap between Jarrah and M14 in an affordable, modern package. Definitely a phono stage to consider.

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