Three (more) amplifiers for the KEF LS50, ELAC Uni-Fi UB5


The most talked about standmount loudspeaker/s of the past twelve months is almost certainly ELAC’s Debut B5 (US$250). Pulling up in second place is the same company’s Uni-Fi UB5 (US$500). Why? Not simply because they each offer outstanding performance for the money but because their designer Andrew Jones knows how to woo the audiophile press with interesting demo music – deadmau5 and RATM played either side of a classical piece at CES 2016 – and his Yorkshire charm.

Before the Jones-fuelled ELAC, it was the KEF LS50 that enjoyed much of the limelight. Interested parties needn’t catch brand ambassador Johan Coorg’s carefully curated audio show demos – although it no doubt helped. The LS50’s coaxial driver array (also seen in the UB5) radical looks (not seen in the UB5) spoke for themselves: “We’re not like the others,” they whispered.

Lie they did not. KEF’s US$1500 standmounts conquered the entry level conversation soon after their 2012 launch, after which they and GP Acoustics’ accounting department never looked back. The front baffle’s ‘50th Anniversary Edition’ text was quietly removed and production was extended indefinitely and so beyond the initial twelve month window.

Last year, a limited run of coloured LS50 saw this reviewer, a long-time fan, trade up from black to red. I’ve had pair of these KEFs knocking about DAR HQ for the best part of four years now.

However, it’s been three years since I suggested three affordable amplifiers as possible dance partners and emails asking about the same continue to roll in. Time for an update, but this time out with one eye on the ELAC affordables [see Footnote 1].


As alluded to by Andrew Jones in our conversation at Munich High End 2016, the UB5 share the LS50’s thirst for power, which often leads to a sting in each loudspeaker model’s affordability tail.

At CES 2016, Jones debuted the Uni-Fi UB5 with “$4000 worth of” Audio Alchemy electronics. He used the same six months earlier at Rocky Mountain Audio Fest. At the Debut B5’s Newport Beach (err) debut, Jones drove them with a Bel Canto C7R whose street price of US$3000 remains over ten times that of the loudspeakers themselves.

Back at home with the LS50, Vinnie Rossi’s 25wpc MOSFET LIO module continues to provide ongoing satisfaction with tough loads, largely attributable to the low impedance, high current output of the LIO motherboard’s ultracapacitor power supply.

Like the Devialet Expert 200, such audible success comes at a price that might seem wholly disproportionate to the LS50’s asking price, even more so the UB5. What’s the wallet watching KEF or ELAC owner to do?


The obvious choice is to get as many watts for as few dollars as possible. If high current output isn’t specified by the manufacturer as an explicit draw card experience tells me that that least 100 watts per channel are necessary to hear the LS50 at (close to) their best.

One sure fire way to get the necessary go juice flowing into one’s entry level standmount is to go Class D which almost always returns a small form factor and an environmentally friendly power efficiency.

Soon after finishing my 2013 piece on a trio of integrated possibilities for the LS50, I took delivery of Wyred4Sound’s ICEPower mAMP monoblocks (US$1999/pair) that offered 250 wpc into 8 Ohms, 430 wpc into 4 Ohms. These were fed both by the matching mPRE (US$1099) and directly from a Resonessence Labs INVICTA Mirus (US$4995). The all W4S rig added greater tonal mass to the leaner, meaner sound of going DAC direct but in either configuration the mAMP’s drew such an enormously wide, deep and internally soundstage from the LS50 that I still talk about it to this day. The catch with the Wyred4Sound mAMP is you gotta run two.


For their S500 stereo amplifier, Utah’s Red Dragon Audio drop a Pascal Class D module fronted by an in-house designed input stage into a single chassis and sell it factory direct for US$1999. Output power is rated at 250 watts and 500 watts into 8 and 4 Ohms respectively. However, bridge a pair of ‘em into mono as I have this year and you’re looking down the barrel at a gargantuan 1000 wpc.

Hooked up to the LS50, the Red Dragons’ big, clean audible personality comes immediately to the fore; there’s a take-no-prisoners attitude to dynamics and transparency that properly reward even the smallest upstream change. The S500 demand a BYO DAC/pre-amplifier.

Going DAC direct, I prefer the PS Audio DirectStream Junior’s (review forthcoming) mellower handling of transient delivery; it serves as a nice counterbalance to the S500’s polished window take on top-to-bottom textural exposure.

Moving over the the Mytek Brooklyn (review forthcoming), DSD’s more laid back disposition is introduced via a Sonicorbiter SE streamer running HQPlayer and with upstream DSD upsampling enabled. What started life as slightly over-etched player outlines as PCM are transformed on-the fly into a presentation that the Red Dragons convey as finessed and delicate.


Don’t want the trial and error of matching (digital) pre-amplifier with a (pair of) shoebox Class D amplifier/s? You’ll need an integrated amplifier that doesn’t skimp on wpc and whose output stage runs in Class A/B.

Ty Pendlebury and Steve Guttenberg’s review of the ELAC UB5 reminds us of their nominal 4 Ohm impedance. The need for high current delivery comes as part of the deal. Then this:

“Finally, we put the NAD C 356BEE amp aside and hooked up a 200-watt-per-channel Rotel RA-1592 stereo integrated amp, and replayed some of the same music over both the Uni-Fi UB5 and RP-160M speakers. Both sounded better, but the Uni-Fi benefited more from the Rotel’s power reserves. The ELAC’s dynamics were now more viscerally felt, and our reservations about the speaker’s punch and energy all but vanished.”


The RA-1592 is a brand new (May 2016) addition to Rotel’s integrated amplifier line-up. So new that I’ve yet to hear it, hence deferring to Pendlebury and Guttenberg. A good time also to remind readers that this post should be seen as a heads up, not a review.

US$2499 nets a 17kg beast that includes MM phono stage, AKM DAC (USB, 3 x coaxial, 3 x Toslink, aptX Bluetooth), pre-outs, subwoofer output, 3 x single-ended RCA inputs, 1 x balanced XLR input and remote control. In other words, the whole nine yards. If it had a network streamer it’d qualify as a super-integrated. The Ethernet port is for applying firmware upgrades or integrating the RA-1592 into an automated control system.

Applied to the UB5 or LS50 the RA-1592 would be for nought if it weren’t for its attendant muscle. As our CNET reviewer duo attest, the Rotel delivers. Its 200 wpc into 8 Ohms comes courtesy of a huge toroidal transformer, one that “won’t sag and distort under complex speaker loads or dynamic signal transients.” Rotel wind their own at their Zhuhai factory – been there, seen that – but the company don’t (yet) specify a power output rating into 4 Ohms.


Our third amplifier choice is also an integrated, one whose output rating might be wholly misleading if it weren’t for the manufacturer’s loud talk of high current delivery and peak power reserves.

Melbourne’s REDGUM Audio spent most of 2015 restructuring their line up of amplifiers. The wood-faced designs of old now make up the Amplifolia range. These remain made in Australia. The more cost effective Black Series see the same Ian Robinson-designed circuits but made in China; the remote control module comes fitted as standard.


The Black Series RGi60ENR drops the Aquillina’s (formerly RGi60) wooden fascia, adds the SineWave heatsink for optimal performance of its MOSFET output devices and wraps the dual mono circuit in a more utilitarian case.

Here, AU$3000 brings home 120wpc into 8 Ohms. However, experience with even the weaker Black Series EGi35ENR, an amplifier that drives the KEF LS50 at DAR HQ like no other modestly-rated integrated should, reminds us that REDGUM watts aren’t like other company’s watts. Theirs are altogether bigger. If you want to approximate the capacious soundstaging of the Wyred4Sound monos but don’t want to go with Class D, this is a fine choice; one whose 180 into 4 Ohms should work very nicely with the ELAC UB5.

Of course, those who don’t wish to play the game of mix n match; or those who think that dropping US$2k+ on associated electronics makes no sense; or those who would rather the connected amplifier/s be tailored to each driver and internalised within the speaker cabinet, you guys can wait for ELAC’s powered version of the UB5 or lobby KEF to activate the LS50.

Further information: Red Dragon Audio | Rotel | REDGUM Audio

Footnote 1: This shouldn’t be seen as an exhaustive list and readers are encouraged to share their own KEF LS50 or ELAC UB5/B5 amplifier pairings in the comments section below.

Written by John H. Darko

John lives in the NOW + HERE = NOWHERE. He derives an income from the ad revenues of DAR. John is also an occasional staff writer for Stereophile, 6moons and TONEAudio.

Twitter: DarkoAudio
Instagram: DarkoAudio
Facebook: DAR


Leave a Reply
  1. Two new options to consider are Legacy Audio’s Powerbloc2 which uses two
    ICE 700ASC modules for 325 watts @ 8ohms & 600 watts @ 4Ohms for $1,600 and the new Emotive amp which uses an ICE 300ASC module for 150 watts @ 8Ohms for $600.

  2. Has there been any word on potential release of the Elac Debut integrated amp? For those more budget-conscious, it may serve as a very nice compliment to the Elac speakers (I have the B6’s).

  3. soma fm (space station soma) > Logitech Transformer > First Watt F7 > Debut B5 (soon Uni-Fi)

    certainly not a rig for everyone, but if you listen at realistic levels (60-70db) for any length of time (I listen 4-6 hours straight most evenings) you begin to get pretty good at detecting fatigue & what causes it (usually solid state & crappy xovers)…I’ve replaced an excellent flea watt tube / single driver setup with with a variety of First Watt amps & the Debuts with fabulous results…the new F7 mated to the ELACS provides musical justice for all from those super barristers of sound, Jones & Pass…yes, the (new) amp is 10x the cost of the ELACS, but so are some of the suggestions above…if you can live without skull crushing db’s, you can get US$10k sound for under $2k (used FW amp / Debut B5 combo)…everyman audio is alive & well…enjoy

  4. Hi John,

    Approximate date when the activated versions will be available?

    In appreciation,


  5. How long do you think that it will take ELAC to begin shipping the active UB5’s?

  6. Being a LS50 and ELAC B5 owner, I really appreciate these insights. I run a Vincent SV236MK2 I picked up with some Schiit. Looking forward to experimenting with new power supplies.

  7. I drive my LS50s with a NAD D7050 integrated digital amp and the combination sounds great to me. This is my first “audiophile” system, though, and i have no real basis to compare. What kind of improvement in the sound, if any, should I expect if I replaced my amp by one of the amps you suggested? Would the difference be substantial? I ask because I do think that the sound I get now is very good (and can get loud without distortion as well).

  8. Hear hear! I am totally with you on the powered LS50 option. Can’t wait. If it ever happens. 🙂 Exciting news about the UB5’s in the meantime though.

  9. There are also some excellent pro amp options or easy to assemble kits that offer cheap watts that can be excellent choices for power-hungry speakers. The Crown XLS line and the offerings from the company named Class D Audio both come to mind.

    I’m generally of the mind to SPEND MOST ON SPEAKERS. So an amp that costs more than the speakers makes little sense to me. Speakers will always remain the biggest bang for your buck improvement or change in sound. So if I’ve got a budget of $3k to spend on amp-speakers, I’m buying $2000 speakers (or maybe even $2500), with $2k, I’m getting $1500 speakers, and with $1k, I’m getting $600-750 speakers.

  10. I have been using the Peachtree Nova 220SE with the LS50s for some time now. Used to run the NAD D3020 but was always wanting a bit more. After trying some other high-powered offerings, I settled on the Peachtree since a used one was available locally. The Peachtree took the LS50s from really good, to great (way better soundstage, and bass control). Now you can get re-certified ones right from Peachtree for $999. With the Peachtree 2.0 stuff coming out, I am seriously considering trading in the 220SE for a Nova 150 or 300. Better DAC, phono stage, and made in North America rather than China. If the phono stage is anywhere close to the Rega – one more box I can do without.

  11. I am looking forward to the reviews of these combinations but especially to the Mytek Brooklyn and PS Junior reviews. Please return from Digital Audio Product Announcement and Show Report to Digital Audio Review 😉 (it has been a month)

    • Even though it still serves as a broad statement of intent for what I do, signposting readers’ expectations, the site’s domain name is woefully out of date. I’m happy to hear suggestions from readers but it gets a little tedious when those expectations come across as a sense of entitlement.

      I’m penning/steering content as I see fit here and this “3 amp” piece is one of the most clicked articles on DAR so far this year so I reckon my decision to write it was a sound one.

      On the PS Audio DAC, I’m waiting for RoonReady sign off. On the Mytek, I’m waiting for MQA content. Both of which are outta my hands.

      For an immediate review fix, might I direct you to

      • I apologize. I did not mean to be pushy. In fact, I like the mix between show reports, reviews, product announcements in combination with your writing style a lot, and should have kept it at that I am looking forward to your reviews without trying to be silly about the name of the site.

        I think I have returned to the 3 amp piece at least twice, but then again I often reread reviews or other articles on DAR (can I please stay? I promise to read some audiostream in the meantime).


        • No problems Edwin – and you’re right about one thing: too much show coverage isn’t healthy for site owner or reader. It’s one reason why I’m taking a pass on next weekend’s Newport Beach show.

  12. With 4ohm dynaudio focus 160 i use a yamaha a-s2100. These speakers are hard to drive too, previously tried an entry level rotel ra-11 (no bass with these, had to dial up the volume to get anything), a rega brio-r (purchased from john, fuller sound more bass) then the yamaha (much cleaner sound than the rega, very tight bass).

    The a-s1100 is cheaper with same amp, just not balanced

  13. Hi John,

    It’s no surprise that these are popular posts, as they’re great tools for the many newcomers who have surely found the hobby by way of the LS50 and UB5. Nicely done.

    The new NuPrime series of hybrid class D amps could be worth a look. The STA-9 seems a good fit for affordable, power-hungry speakers at US$650 for 120 quality watts, bridgeable to 290 watts.

    NuPrime also has the DAC-9, which offers much of the Mytek Brooklyn’s Swiss Army Knife functionality (analog input and volume control) for less than half the cash. If it ever crosses your path I’d be interested to hear how the two compare, sound wise.

  14. Any chance the Peachtree Audio Nova (just the plain “Nova”) can run the LS50 at moderate levels adequately (at least until I can invest in some more serious power)?

  15. Several sites claim that the Naim UnitiQute 2 will drive the LS50 to satisfaction – however it’s specs say it’s only 30W per channel…is this another case where “Naim watts are different than most company’s watts”? Based on your previous testing, I am sceptical…

  16. In the intimate desktop field I’m content with a Nad D7050 powering my Frosted Blue LS50’s, and two Vaf MPB SW2 subwoofers serving as “stands” for the Kefs.

  17. The LS50 were paired with a Rotel R-12; then upgraded to a Creek Evolution 100A – I think the LS50 are still thirsty for more juice. But the Creek has the other features with the RUBY DAC – making it a complete integrated system with a fine FM tuner. (and I can’t return it) Has anyone experimented with a powered subwoofer (REL t-zero) to remove some amp demands on the LS50s?

  18. Semi-newb audio guy here. Just purchased 4 UB5s and a UC5 for home theater use. Considering adding 2 more for 7.1 and using a Denon X3200, 3300, or 4200.

    Do you think the following would be necessary/a good option sound quality wise?

    Outlaw Audio Model 5000 power amplifier $600

    Great reviews and seems like a best bang for the buck option. Thoughts? Negatives?

  19. Guttenberg raved about the Schiit Ragnarok + LS50. I’ve just set up a Ragnarok with the UB5”s and while i’ve not had a chance to push them hard my first listen suggests the Ragnarok handles them just fine with 100w into 4 ohm.

  20. I’ve had the LS-50s and currently have the UB5s, they’re part of a second system (Harbeth and Quad in the main). I had a terribly hard time finding a good amplifier mate for the Kefs. They liked my old Accuphase e303x the best but the pre section of that integrated is rather dated in sound. I never felt I had enough power for those speakers so moved on from them. But I moved to a place with a smaller room for my second system and recently bought the UB5s. I have to say, I love these speakers like I never loved the Kefs, though I’d like to have had them here for comparison in this smaller room. The Elacs sound good on my little Leben tube integrated, they absolutely love my modded Dynaco stereo 70, and did great on and old Heybrook P2 amp. The pre/Dac is a BMC. The Elacs really take to the two amps.

    I really think these little Elacs are fantastic. I’ve never had another pair of speakers cheap or expensive that was so easy to find a good amp match for. I would say this is the best few hundred dollars I’ve ever spent in this hobby. They’re not going to replace my Harbeths, but I could live with them if budget and/or circumstance dictated it. I’ve heard many more expensive speakers that I’ve liked less, including Elacs previous, much more expensive, efforts.

  21. Love my original KEF LS50 5Oth Anniversary speakers! At first I used a NAD C 316bee which was fine but no where near the ‘power’ they need to sound great. Switched to Rogue Sphinx and all was good, much better fuller sound.

    Now I’m thinking about changing directions – Raven Audio Nighthawk: 20wpc tube amp!