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KEF loudspeakers: amplifier matching with the Blade Two & LS50

  • There’s no prayer like desire. At the Munich High End show last year, KEF launched the Blade Two, a downsized take on its popular Blade floorstander with dimensions and sticker price hacked back to reach those in smaller living spaces and/or with thinner wallets.

    The Blade Two contains just as many parts as its forerunner but they’ve been condensed into an enclosure that measures two thirds the volume. Bass driver size has been reduced by a third too – from 9” to 6” – and the top quarter has been lopped from the MSRP: the Blade Two sell for US$24K.

    However, at that very same 2014 event KEF was also launching the equally new but more traditionally-styled Reference Series. Relegated to static display, the Blade Two sat dutifully silent on the sidelines while the Reference One pounded out its stuff, powered by Arcam amplification.

    At the Munich High End this year, KEF let the Blade Two loose, showing precisely how the aspirational audiophile can have his cake – terrific sound – and eat it whole without the starchy aftertaste of aesthetic conservatism. The Blade Two look incredible, sounds even better. If there was a Best in Show for this commentator at the M.O.C. in 2015, KEF’s Blade Two were it — and judging from his own show report at 6moons, I’m confident Srajan Ebaen agrees.

    The new Blade Two owner must then ask: “Which amplifier?” With the Hobson’s choice of Johan Coorg’s show room demo, KEF once again demonstrate what’s possible with Arcam electronics and as good as this particular pairing sounded in Munich (and simultanesouly echoing the audiophile’s curse), I’ve convinced myself that better is just around the corner. Looks wise the Blade (Two) scream for something from Devialet’s recently re-christened Expert Series. I know Ebaen’s angling for a Blade Two to review (or even own) and given his forensically thorough approach to the review craft, amplifier-matching intel will spill in time.

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    Stateside, KEF America do the show and tell with Parasound electronics. Per Munich, it’s just as likely that this demo space partnership is born of regional commercial alliances as it is of optimised sonic performance. I hear nothing to complain about when the standmounted LS50 are driven by John Curl’s Halo range but I also know from back-to-back showroom auditioning with the Magnepan 1.7 in Australia that the Sanders Magtech (for example) is a more revealing amplifier, far more capable of micro-dynamic avidity and separation.

    The LS50 standmount was orginally intended as a limited edition model to celebrate KEF’s 50th year in the hi-fi biz but consumer demand proved so strong that they sensibly decided to continue its production indefinitely. Genetically engineered with the Blade’s DNA, the LS50 is another example of KEF coming good on both sonic and aesthetic impact. The coaxial driver advancements made whilst developing the original Blade at KEF’s R&D facility in Kent also feature in the LS50. And thanks to a hefty push for alternative clothing from KEF’s Hong Kong owner GP Acoustics, the LS50’s curved front baffle, rose-gold Uni-Q driver array and piano black finish position it as a seriously progressive looking piece of audio furniture.

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    Back in Sydney and back on an entry-level streak, DAR has scored another long-term loaner on a pair of LS50 thanks to the generosity of KEF’s Australian distributor. Not for formal review you understand but to extend the investigation into price-appropriate amplifier matching territory. 2013’s first installment remains one of DAR’s most visited posts, possibly reflecting the LS50’s unerring popularity in the budget sector. I can’t think of another standmount at US$1500 that I would recommend over and above the LS50. Several Stateside reviewer colleagues agree.

    Furthermore, I receive more emails about the KEF LS50 than any other loudspeaker. Readers want answers to the never-ending conundrum that comes with owning passive loudspeakers: “Which amplifier do I gots to get?”

    Fresh from its victory lap with the super-affordable Pioneer SP-BS22-LR standmounts, I asked myself: how would the NAD D 3020 respond to time spent further upstream? Would NAD’s future-facing entry-level integrated cut it with a loudspeaker costing thrice its own asking price?

    For those looking for a short cut to the brutal truth the answer is no. The NAD’s vocal clarity, so enjoyable via the Andrew Jones-designed Pioneers, morphs into inner-throat strain at the hands of KEF’s US$1500 standmounts. A result that showed up for tea despite D/A conversion being offshored to a Resonessence Labs Concero HD, itself fed by an Antipodes DX server. Loudspeaker cable used was AudioQuest’s Rocket 88.

    Listening for longer to the NAD/KEF combo exposes the pairing’s shortcomings with the dynamic charge, specifically that demanded by Belle & Sebastian’s “Enter Sylvia Plath” (whose refrain could easily double as a Pet Shop Boys outtake). The NAD runs out of puff before the Rega Brio-R and even on a micro level the guitar-strummed transients that bounce around this song’s outer limits adopt more of a metallic sheen when reproduced via the NAD. Guitar strings sound more natural at the hands of the Rega.

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    Staying with the NAD but switching over to New Order’s eighties classic “Thieves Like Us”, detail focus remains strong but the LS50 exposes the NAD’s tendency to line the eyes of the song’s synthesiser-driven melody with chromatic aberrations. Next to the Rega’s marginally fatter tonal mass and moister textures the NAD sounds thin and reedy.

    It’s worth noting that the Brio-R’s 60wpc (into 8 Ohms) is double that of the D 3020 and the Rega runs in Class A/B whilst the NAD uses Class D, specifically Hypex’s UcD. Whether any of the audible deltas is attributable to these differences is for engineers to quibble over.

    Consideration might also be given to differences between the loudspeakers themselves. Both loudspeakers models come in at 85db sensitivity and yet the NAD integrated performs admirably with the SP-BS22-LR but less so with the LS50 – the admiration falls away.

    Lenbrook’s promotional propaganda promises consistent performance from the NAD D 3020 – its UcD output stage is designed to be more (impedance) load invariant than that of the Rega. The Brio-R’s manual explicitly recommends partnering with 8 Ohm nominal loudspeakers and than sustained exposure to 4 Ohm loads will cause the “the case to exceed 40° C above the ambient temperature”. Bang on. After half an hour driving the 4-Ohm-stable Magnepan MMG to half-decent SPLs, the Brio-R’s case becomes almost too hot to touch. Flipping it around, real-world application lays plain the Rega’s greater comfort in an around an 8 Ohm ‘safety’ zone with only sporadic exposure to impedance dips.

    Perhaps the Brio-R’s strengths are more apparent when dueling on the LS50’s (nominal) 8-Ohm more level playing field than with the Pioneer’s (nominal) 6 Ohm load stacking the odds against its ability to keep pace with the NAD?

    Perhaps it just took a more copacetic loudspeaker match for the Rega to reveal itself as a more satisfying amplifier? Functional differences aside, I prefer playing Brian Eno’s Before And After Science with the Rega Brio-R hooked up to the KEF LS50.

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    That said, I wouldn’t recommend either pairing to the dyed-in-the-wool audiophile looking to max out returns on his LS50 investment. For that we must shift focus to the high current delivery of Vinnie Rossi’s LIO or the REDGUM RGi60. And if you can’t go high current, go high output power. Digital dudes are directed toward the Peachtree Nova125SE or Wyred4Sound mINT whilst phono fanatics should consider the Rogue Audio Audio Sphinx.

    What’s best with the KEF LS50? I’ve not heard everything – an impossible task – but no amplifier has yet matched a pair of Wyred4Sound mAMPs for soundstage enormity, internal capaciousness and layer separation, into which going DAC direct will save you dollars but adding a pre-amplifier proper will beef up tonal mass and muscularity.

    Of course, KEF could end all the sturm und drang of amplifier matching soon enough if it re-applied the Hifi-your-computer logic (that birthed the two X300A models) to the LS50, thus bringing an active model to market. Just sayin’, always prayin’.

    Further information: KEF | KEF America | NAD | Rega Research | Advance Audio Australia

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    John Darko

    Written by John Darko

    John currently lives in Berlin where creates videos and podcasts and pens written pieces for Darko.Audio. He has also contributed to 6moons, TONEAudio, AudioStream and Stereophile.

    Darko.Audio is a member of EISA.

    Follow John on YouTube or Instagram

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