RA280

Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (i5, 256GB SSD, 40GB RAM, Sonoma 14), 4TB external SSD with Thunderbolt 3, Audirvana Studio, Qobuz Sublime, Singxer SU-6 USB bridge, LHY Audio SW-8 & SW-6 switch, Laiv Audio Harmony and Sonnet Pasithea; Active filter: Lifesaver Audio Gradient Box 2; Power amplifiers: Kinki Studio EX-B7 monos & Gold Note monoa on subwoofer; Headamp: Kinki Studio THR-1; Phones: HifiMan Susvara, Meze 109 Pro; Loudspeakers: Qualio IQ [on loan] Cables: Kinki Studio Earth, Furutech; Power delivery: Vibex Granada/Alhambra on all source components, Vibex One 11R on amps, Furutech DPS-4.1 between wall and conditioners; Equipment rack: Artesanía Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc amp stands; Sundry accessories: Acoustic System resonators, LessLoss Firewall for loudspeakers, Furutech NCF Signal Boosters; Room: 6 x 8m with open door behind listening seat
2nd system: Source: FiiO R7 into Soundaware D300Ref SD transport to Cen.Grand DSDAC 1.0 Deluxe; Preamp/filter: Lifesaver Audio Gradient Box 2; Amplifier: Kinki Studio EX-M7; Headamp: Cen.Grand Silver Fox Loudspeakers: MonAcoustic SuperMon Mini + Dynaudio S18 sub; Power delivery: Furutech GTO 2D NCF, Akiko Audio Corelli; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan]; Sundry accessories: Audioquest Fog Lifters; Furutech NFC Clear Lines; Room: ~3.5 x 8m
Desktop system: Source: HP Z230 work station Win10/64; USB bridge: Singxer SU-2; DAC: iFi Pro iDSD Signature; Head/speaker amp: Enleum AMP-23R; Speakers: Acelec Model One Headphones: Final D-8000 & Sonorous X, Audeze LCD-XC, Raal-Requisite SR1a on Schiit Jotunheim R
Upstairs headfi system: FiiO R7; Headphones: Meze 109 Pro, Fiio FT3
2-channel video system: Source: Oppo BDP-105; All-in-One: Gold Note IS-1000 Deluxe; Loudspeakers: Zu Soul VI; Subwoofer: Zu Submission; Power delivery: Furutech eTP-8, Room: ~6x4m
Review component retail: £2'999

Bonkers and less bonkers.

A rose is a rose is a rose; until it's a Hifi Rose. From Stein to Seoul in a sentence. The brand made serious inroads into the server/streamer sector with its full-width touch screens mounted flat to the face plate. Their RA180 integrated shown in the above underlay broke the Internet with its steampunk knobbery and features including high-pass outputs for super tweeters. Those who dug the styling but wished for just a bit more restraint now have the RA280 which trims the fat fantastic but retains selectable ±15dB tone controls centred on 100Hz and 10kHz, MM phono, dimmable VU meters and a magnetic circuit breaker in lieu of a mains fuse.

Like their colleagues at AGD, Java, Merrill, Mytek, Orchard and Peachtree, our Koreans implement their dual-mono 250wpc/8+4Ω class D outputs with 800kHz-switching GaNFets not silicon Mosfets. The usual claim for these parts are 1/10th the transitional dead times between on/off states; and gentler output filters. The Hifi Rose switch-mode power supply gets silicon carbide field-effect transistors. And by the way, this gig came about with the cooperation of Hifi Rose's UK PR man Murdo Mathewson of Ginger Dog Comms and Simon Powell of Henley Audio, their British importer. It squashed down shipping pains from 2-way Seoul ⇔ Shannon mileage to a short skip across the Irish sea. Time for the obligatory Irish joke involving a Brit and Scot.

Tidy layout and construction.

An Englishman, a Scot and our man Paddy O'Connell boast about how famous their uncles are. "My uncle is a bishop," says the Englishman. "When he walks down the street, everybody says, Your Lordship." "My uncle is a cardinal," says the Scots. "When he walks down the street, everybody says, Your Eminence." "Dat's nothing," says Paddy. "My uncle weighs twenty-nine stone. When he walks down the street, everybody says, God Almighty!"

If from the above photo you wondered "where's the actual amplifier", say hello to the next top-left image. Voilà, two densely populated small vertical PCB backed by heat sinks. Modern class D needs no more. Leave the God Almighty stones to high-power class A with linear power supplies. This amp only needs 9.5kg to do the ¼ kilo-watt job in very fine threads. The below photo to the upper right shows the phono module. The 500W SMPS and graph for the bass/treble controls are both self-explanatory. We need the spec sheet again for 30mΩ output impedance, 47kΩ input impedance, 0.007%/125W THD and 10Hz – 85kHz ±3dB bandwidth. For i/o we get 3 x RCA, 1 x phono, 1 x XLR and a mono 1Vrms subwoofer output.

And of course there's the black or silver finish and stylish 38kHz remote. The factory warranty is 1 year. What there isn't is a headphone port or amp-direct input to bypass the preamp stage.

If your last class D reunion dates back 15 years, you've missed a lot of progress. From Devialet's 1-watt class A module driving class D multipliers to Merrill Wettasinghe and Alberto Guerra baking their own independent gallium-nitride power stages, the latter inside tubes; from Hypex UcD advancing into nCore then Purifi Eigentakt to S.P.E.C. of Japan voicing TI-based class D to tube + horn-system precedents; from Sven Boenicke massaging Powersoft's class D with extremist tweaks to ICEpower, Pascal and everyone else I forgot or don't know of… pulse-density modulation amplifiers have evolved from early subwoofer use. In very simplistic terms, class D describes an analogue signal as a series of rapid pulses of discrete duration. Think of what Morse code did for our alphabet's 26 letters. Then scale up that idea on complexity and pulsing speed to class D. DSD does something related. Whilst real engineers will cough over such basic language, for us it's close enough. By now everyone appreciates that class D packs far higher power density and runs far more efficiently than class A and AB. It converts more wall power into sound so wastes far less as heat. Whilst switch-mode power needn't be married to class D—Aavik and LinnenberG make push/pull class A amps with MeanWell SMPS, AGD's flagship runs class D off linear power—those two technologies do tend to go hand in hand. That's because SMPS too are smaller and lighter than their linear brethren to abscond with hulking mains transformers, big coke-bottle capacitance banks and 50/60Hz mains noise. In short, class D goes green. It's the currently most future-friendly class of amplifier operation. Where that resonates, the RA280 has us covered. It doesn't just run cool but looks it. Will having our environmentally responsible cake and eating Hifi Rose's styled sex appeal extend to sonic bliss in the seat? Or must something give because (cue grandpa) we just can't have it all?