Mordaunt-Short has long been known, first and foremost, for its high-value budget loudspeakers, a tradition that current owners Audio Partnership has rigorously maintained.

However, developing an upmarket 'flagship' range makes good sense, as it provides a technology test bed for new ideas that can subsequently 'trickle down' into more affordable models.

This £4,000 per pair Performance 6 Limited Edition is a subtly revised variation on the Performance 6 theme introduced in 2004. Although this LE version carries a £500
price premium, the two models look visually identical, apart from the colour, which is only available in high-gloss 'Midnight Black' (as distinct from 'Granite Grey' and 'Brilliant Silver').

Top quality redesign

The similarities might be obvious - the same elegantly shaped enclosure, the same metal diaphragm drivers operating in the same three-way, four-driver configuration.

The differences with this LE variation are exclusively under the skin, specifically in the crossover network and enclosure - two areas where increasing refinement has brought substantial gains for a number of brands in recent years.

Improved crossover network performance through careful selection of audiophile-oriented components, has been having a major influence on upgrading loudspeaker sound quality.

Recognising this, the Performance 6 LE's network has been redesigned around a new printed circuit board, using Mordaunt-Short's established DVP (dual value parallel) capacitor technique with high-quality polypropylene types from noted specialist ClarityCap.

Elegant styling

"Wood is not an engineering material", was a catch phrase used when Mordaunt-Short first launched the Performance 6, to stress the several advantages that accrue through moulding an enclosure from a polymer resin.

It's a fair point, as wood - even when 'mashed-up' into sawdust and then bonded together again with wax and resin as MDF - does have certain limitations, mostly because it's normally formed into flat sheets of constant thickness.

And although it's true that MDF is much more machinable than chipboard or plywood, there's no denying that a moulded monocoque type structure offers several potential advantages.

The most obvious of these is the irregular and exceptionally elegant shape. All surfaces are curved, and the whole thing is strongly tapered so that it's slim and very shallow at the top, but slightly wider and considerably deeper down at the base.

Curved surfaces are much more rigid than flat ones and also ensure that internal reflections are well scattered. They also ensure that tightly focused standing waves aren't created.

Moulding allows for much more complex shapes inside and Mordaunt-Short has taken full advantage. The drive units are actually bolted to rods that extend forwards from the thick rear spine of the enclosure, while strategic ribs reinforce the sides.

Inside the speaker system

For this LE version, the polymer resin has been re-formulated to give better performance, and internal details refined to improve the bass. Grilles are supplied to cover each driver individually, but stickers suggest it's better if they're not used. Only the coarse mesh protecting the tweeter is a permanent fixture.

This a full three-way design, featuring four metal-diaphragm drive units arrayed up the front above a flared reflex port. The twin 165mm bass units have M-S's familiar silver dished metal diaphragms, 120mm in diameter with little radial stiffening ribs near the periphery. The midrange unit looks like a smaller version, though its 75mm diaphragm is rib-free and driven with help from compact neodymium magnets.

The tweeter is arguably the most interesting driver of all, the whole assembly is roughly more than 20cms deep, featuring a complex fat metal rod behind the diaphragm that's drilled by a logarithmic spiral of thin, differentially tuned pipes. The purpose is to create a flat acoustic impedance at the rear of the diaphragm, while also allowing through some non-coherent treble output to add extra air and spaciousness.

A hefty baseplate is invisibly incorporated in the base of the enclosure, ensuring fine physical stability and secure spike accommodation. However, the spikes themselves put form ahead of function - they look stylish, but the lock-nuts can only be finger tightened. Three matching pairs of terminals are mounted low down at the rear.

Exceptional balance

The Performance 6 LE is clearly intended for free space siting, well clear of walls, as was amply confirmed in the far-field averaged in-room response traces.

These showed an exceptionally good overall balance right across the audio band, from a -6dB point at 22Hz (under in-room conditions). The trend was unusually even throughout the bass region and also exceptionally smooth above 300Hz, though there's a touch of over-exuberance in the mid-treble, 5-7kHz.

The measurements were very similar indeed to those made on the original Performance 6 under similar conditions some three years earlier, though there were a couple of minor differences. The impedance traces were very similar indeed, but the LE shows slightly more low bass damping.

Sensitivity came out at 88dB on our tests, a decent enough figure (if a tad below the 89dB claimed), but the load the amplifier has to deal with is quite demanding through the bass region.

The top end is arguably a shade hot, but it's also delightfully sweet, open, well integrated and never sounds forced, while bass always sounds controlled, as well as satisfyingly deep and powerful.

Precise imaging

Put on the Chemical Brothers, wind up the volume as high as you dare and then touch the sides of the enclosure. Hardly any vibration comes through, so it's obvious that the radical enclosure is doing a very fine job.

That's further emphasised by the lack of boxy effects and the airy-but-precise stereo imaging. One simply isn't conscious that the sound is emanating from two reasonably large enclosures - you simply hear the music, and the stereo mix, with fine focus and freedom from boxiness.

Though most of the news is very positive, transparency and image depth did seem somewhat limited and dynamics sounded a little constrained. The bass end, in particular, sounds a trifle congested and lacking a little freedom of expression.

Rather than underpinning things and taking the lead in driving the music along, it sort of hangs on in there, doing what's necessary and keeping good time, but not really taking over the control or the initiative.

Play as loud as you like

Dynamic range, however, is thoroughly impressive, presumably thanks to the very low enclosure 'signature', so low level detail comes through well. Instrumental textures are well portrayed and with ensemble material it was quite easy to distinguish the number of brass or string instruments playing.

Colorations are very low, too and speech sounds unusually clean of any undesirable cuppy or nasal effects.

On the end of a largely Naim-based system, the overall character might be a little cool and lean for some tastes, so we exchanged our regular speaker cables for the slightly richer and fuller sounding Chord Signature, to good effect.

However, the biggest strength of the Performance 6 Limited Edition must be its ability to sound sweet, open, coherent and detailed even at very low listening levels.

At the same time, this new LE version remains happy and free from aggression when being played seriously loud, too.