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Sonner Audio Legato Duo Loudspeaker

Sonner Audio Legato Duo Loudspeaker

I have to admit that Boston-based Sonner Audio was unfamiliar to me until I read colleague Andy Quint’s 2018 AXPONA report. He was impressed with the potential he heard under arduous show conditions (“Satisfying orchestral weight and timbral nuance were evident even on a brief audition”). Such audio qualities have always been near and dear to my heart, so I was eager to have a listen to this new kid on the block.

Sonner Audio is led by president Gunny Surya—a music and audio enthusiast with a background in industrial engineering, a Master’s in business, and 20 years of experience in technology and industrial companies. Mr. Surya stated: “We apply world-class operation/business practices to Sonner’s operations, such as using state-of-the-art software and tools for speaker design, measurements, QC, CAD/CAM for cabinet design, and CNC machines for cabinet fabrication. We work with well-established companies around the globe to supply our crossover components, speaker drivers, and cabinet material.” Currently Sonner Audio offers two product lines—the two-model Allegro Reference series and the lower-cost three-model Legato Series, with the Legato Series featuring trickle-down technology from the Allegro Reference.

Visually the $8500-per-pair Legato Duo is easy on the eye with soft curves, a slanted baffle, and a rounded-back enclosure. Carefully offset and affixed to its platform base, the speaker is remarkably stable given its sloping angle. This is a two-and-a-half-way, bass-reflex floorstanding design with a driver complement that includes a 1″ ring-radiator tweeter, a 5.5″ coated-paper-cone mid/woofer, and a 6″ custom-designed aluminum woofer. A pair of ports are positioned at the rear of the speaker. The crossover frequencies have been set at 200Hz and 2.5kHz. The svelte cabinet doesn’t employ traditional box-enclosure back and side panels; rather, the enclosure is pressed into shape and then machined into its final form via three- and five-axis CNC into a single curvilinear monocoque designed to reduce internal standing waves and minimize energy storage.

The Legato Duo is acoustically time-aligned as suggested by the raked front baffle—a look reminiscent of slanted-baffle designs like those from Thiel and Vandersteen. Sonner’s design philosophy is to maintain flat frequency response and minimize impedance variations to make its speakers easy loads for amplifiers to drive. Internally, only point-to-point wiring is used (no circuit boards) and components are carefully laid out to minimize electromagnetic interference.

High-quality components and tight tolerances optimize the integration of speaker drivers via Sonner’s “Panoramic Crossover” topology. Sonner maintains that all machining, assembly, and finishing is done with U.S. craftsmanship to assure a reliable and consistent product. Handsome, single-wire, copper-alloy binding posts add a stylish touch. In a clever nod to both aesthetics and function, the baffle’s leather panel is part of the time-alignment design, and it can be covered with a magnetically attached grille.

For this review I powered the Legato Duo with the MBL C51 180Wpc integrated amp with great results. Wire, both speaker and interconnect, was courtesy of Tara Labs (review forthcoming), with Audience Au24SX power cords and an Isotek power conditioner (review forthcoming). I found the Legato Duo easy to drive, but it benefitted from the added control that the MBL afforded from the lower mids on down.

In sonics, the Legato Duo played it straight down the middle with an invitingly warmish signature that seemed to make music more listenable rather than challenging to the ear with excesses at the extremes. The mids demonstrated a presence range of good articulation without veering into forwardness. In transient behavior, the Legato Duo seemed fast in the same way some of the fine designs from Audio Physic speakers have been. Crash cymbal, high-hats, snare-drum transients, and flat-picked instruments really sprang forth with a sparkle that conjured the real thing. And solo violin had a nice balance of aggressive bowing and attack without sacrificing the critical resonant sweetness of the body of the instrument.

The Legato Duo did not overreach in the upper octaves, thereby avoiding peakiness and sibilance; it did not puff itself up in the bottom octaves, either. Treble response was smooth, not quite as bloom-filled and airy as some tweeters but highly listenable. Inter-driver integration and coherence were also good with little sense of tweeter-on-top/woofer-on-bottom discontinuities.


The lower midrange descended into the midbass fairly smoothly, with good clarity providing cello, bassoon, and bass violins the requisite resonance body they deserve. As I listened to Harry Connick, Jr.’s cover of “A Nightingale Sang in Berkeley Square,” I was impressed by the amount of air the Duo managed to move to capture the throaty bell sound and brassy resonance of Branford Marsalis’ tenor sax solo. It didn’t quite have the full weight that my reference ATC SCM50 ASLT offers, but it was very good for the segment where the Legato Duo competes.

The bottom-octave range (20-40Hz) was a bit beyond the reach of this 43″-tall, mid-sized two-and-a-half-way; still, there was perceivable response in my room below forty cycles, which conveyed some of the seismic flavor of the deepest octave. Though the Legato Duo’s low-frequency response rolled off fairly steeply, the drivers still moved a notable amount of air, giving the speaker a heavier footprint than might be expected at first glance.

Vocals were another strong suit for the Legato Duo. Nicely balanced, firmly weighted in space, male and female singers were reproduced with liveliness, good attack, and a non-aggressive sibilance range. The Diana Krall track “I’ll See You in My Dreams” was perhaps most instructive. Krall’s voice—a torchy, playful alto—was nicely centered and realistically scaled on the stage. Even when challenged to reproduce Nirvana’s Kurt Cobain singing “Come as You Are,” the Legato Duo demonstrated good control and composure with little obvious midband compression. Cobain’s vocal was reproduced with a good balance of its characteristic grit and melodic intensity.

I then cued up my “go-to” piano recordings and found a very pleasing, even romanticized sound with good resolving power, solid midband dynamics, and a fairly wide macro-dynamic envelope. During Evgeny Kissin’s performance of Glinka’s “The Lark,” I could hear the resonant body of the soundboard of his concert grand piano very clearly. During some arpeggiated crescendos a hint of upper-octave glassiness crept in, but the articulation of these difficult passages was very good. Similarly, on Clark Terry’s recording of trumpet/piano duets One on One, I felt that the piano tended to sound a bit dry and harmonically thinned down slightly during heavily punctuated treble notes.

Image stability was an area where the Legato really hit its stride. As I listened to MoFi’s latest One-Step LP of Simon & Garfunkel’s Bridge over Troubled Water, I was taken aback by the amount of detail and layered depth that was being revealed on classic tracks like “So Long, Frank Lloyd Wright” and “Cecilia.” The Legato reproduced sound in the way a topographical relief map indicates elevation and coordinates—it was as if the sonic longitude and latitude of images were carefully charted beforehand. This was a wonderfully silent cabinet that seemingly betrayed little in the way of resonances.

Ultimately, a little low-end dynamic compression came to the fore—a limitation perhaps best explained by the two-and-a-half-way configuration. As I listened to the Manhattan Jazz Quintet’s “Autumn Leaves,” the macro-dynamic gradients during Soloff’s crackling trumpet solo could have been more explosive. The sustain and complexities of deep bass could have been better explored and extended. For example, during the “Vivo” section of Stravinsky’s Pulcinella Suite the trombone/acoustic bass duet indicated a hint of smearing, as these two heavyweights tangled like a pair of cape buffalo. Nonetheless, the Legato Duo still retained a marvelous sense of the dimensional world of soundspace, and a strong if not fully realized impression of venue.

The Legato Duo is not without hard-charging competition. An obvious challenger would be the Vandersteen Audio Treo CT ($8400) I reviewed in Issue 262. Like the Legato Duo the Vandy lays the baffle back to phase-align the drivers, but unlike the Legato it has the added lower mid/upper-bass thrust and extension of a four-way. The Vandersteen requires more power, however, to show its best. In smaller rooms the slightly narrower spectral balance of the Legato makes it easier to optimize than the Treo CT.

Getting to know an unfamiliar brand of loudspeaker is always a bit like stepping into thin air without a parachute. And sometimes it doesn’t matter how much you’re pulling for a product to be good; it’s not always meant to be. So, in the case of the Sonner Audio, it’s truly gratifying for me to find myself in agreement with the positive impressions of a fellow reviewer whose work and ear I respect. I consider this a fine effort and an even finer debut. It’s a welcome addition to the high-end neighborhood.

Specs & Pricing

Type: 2.5-way, ported enclosure
Driver complement: 1″ tweeter, 5.5″ coated-paper-cone mid/woofer, 6″ custom aluminum-cone woofer
Sensitivity: 90dB
Frequency response: 37Hz–23kHz
Nominal impedance: 4 ohms (minimum, 3.8 ohms)
Dimensions: 15″ x 43.4″ x 26.7″
Net weight: 65 lbs.
Price: $8500/pr.

68 Daniel Webster Highway
Merrimack, NH 03054
(603) 881-3978

By Neil Gader


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