Each Duo incorporates two 125W Class D amplifiers, with the crossover and other signal processing performed in DSP. DSP crossovers permit any filter characteristics, along with the ability to correct for driver behavior. In addition, DSP crossovers obviate the need for signal-robbing capacitors and inductors between the amplifier output and the drive units; the amp output is connected directly to the drivers’ voice coils. The arrangement also means the system is bi-amped, another advantage. And the driver designer knows what amplifier will be driving his product, and the amplifier designer what speaker the amp will be driving. Consequently, this crucial interface can be engineered as a unit to work together optimally.
The attractive and sturdy metal stands, which can be filled with sand for greater stability and vibration damping, are a $799 option. Two types of spikes are included, one set with sharp points and one with rubber feet. The stands and the speakers themselves are available in matte black or matte white finishes.
The Duo supports Apple AirPlay 2, Spotify Connect, Bluetooth, and is Roon ready, with a 60-day free trial of Roon included. Unfortunately, the Duo doesn’t incorporate MQA decoding. The system can accommodate up to 24-bit/96kHz audio. To take advantage of the Duo’s high-resolution capability, however, you’ll need the $699 Formation Audio network hub. This hub accepts analog and digital signals from multiple sources, encodes those sources in Bowers & Wilkins’ proprietary wireless format, and distributes the signal to any Formation product on the network. Any number of Formation products can connect to the proprietary mesh network for whole-house wireless audio. As you can read in the sidebar, the wireless network is significantly more advanced than standard off-the-shelf solutions employed by other manufacturers of integrated wireless loudspeakers. It is reportedly ten times faster, has lower latency, is more robust and easier to set up, and most importantly, delivers better sound quality than existing wireless systems. This superior sound quality is realized by reducing the variable latency between the left and right wireless signals driving the loudspeakers, which is reportedly a problem for conventional wireless.
The Duo (and any other Formation product) is set up through the Bowers & Wilkins app; you plug in the components, launch the app, and after a few taps, the Formation products are connected to the network. You can stream music directly to the Duo, but the experience is so much richer with Roon (as noted, a free trial is included with the Duo). Once you use Roon there’s no going back. This was my first experience with the software, and it is a wonderfully amazing product—not just for handling the mechanics of selecting music, but for encouraging you to explore a music library as well as discover new music. I set up my Windows PC as the Roon Core, and then selected and managed my music library and streaming services through Roon Remote on an iPad. Setup was extremely simple and worked the first time.
The Formation Audio wireless hub takes in analog and digital signals, converting them to the wireless stream sent to any Formation product on the network. It offers TosLink digital input, stereo analog input on RCA jacks, a digital out, and an analog output. Connectivity, as previously noted, includes Apple AirPlay 2, Spotify Connect, Roon Ready, Ethernet (RJ45 or WiFi), and Bluetooth. The integral DAC operates at 192/32. The Formation Audio syncs all devices across the network; you can listen to the same source in all rooms, or simply push a front-panel button on any Formation product to cycle through sources driving that particular unit. Setup was by far the easiest I’ve encountered with any wireless product. I connected the record-out jacks from the Constellation Altair II preamplifier to the Formation Audio’s analog input, which allowed me to listen to any source (Basis Transcendence turntable or Berkeley Alpha Reference DAC) through the Duo.
The Duo immediately impressed with its smooth tonal balance, full bottom end, and wide dynamics. But the Duo had an almost startling clarity and alacrity through the midrange that elevated the performance beyond what one would expect from a system of this price. The Duo’s transparency and presence were simply sensational, giving vocals and lead instruments a lifelike immediacy and tangibility. Paradoxically, I would guess that the frequency response from the presence range through the lower treble had a very slight and broad dip. A somewhat recessed midrange usually works to reduce the sense of immediacy, but the Duo’s clarity and transparency overcame a slight reduction in upper-midrange harmonics to present images that were fully fleshed out tonally and spatially. In fact, the Duo had an almost spooky sense of presence. Buddy Guy’s closely miked vocal on the track “Done Got Old” from the album Sweet Tea, accompanied only by his spare acoustic guitar playing, had an intimacy and directness that powerfully communicated his world-weary delivery. In addition to the midrange clarity and lack of coloration, the sense of presence was heightened by the extraordinary image focus and sense of bloom around instrumental outlines.
Significantly, the upper midrange and treble were extremely clean and smooth, without coarse textures or a glassy sheen. These qualities contributed significantly to the Duo’s exceptional overall musicality and absence of listening fatigue. This is pure speculation, but it’s possible the Duo’s designers balanced the speaker with this easy-going upper-midrange and treble to compensate for the hardness and glare endemic to lossy streaming services such as Apple Music and Spotify. The majority of Duo buyers will likely use one of those two sonically compromised services without knowing that there are much better-sounding options in Tidal Hi-Fi and now Qobuz. Nonetheless, the combination of a slightly laid-back midrange, detailed yet not overbearing treble, and midrange liquidity went a long way toward my overall impression that this was a musically compelling system.
The Duo’s bass was warm, rich, and full rather than lean and tight. The midbass had a bit of a bump that compensated for the lack of true extension. This gave the system more tonal weight and gravitas than expected from a single 6.5" woofer. Extension was surprisingly good within the physical limitations of the smallish cabinet. Remember that a woofer under DSP control in a sealed cabinet isn’t bound by the usual laws of physics that dictate the roll-off characteristics of a passive loudspeaker. In other words, the designer can realize deeper extension (within the driver’s mechanical limits and the amplifier’s output power) than is possible in a passive speaker of the same size. Consequently, the Duo’s bass was credible on Joey DeFrancesco’s Hammond B-3 pedals on the Bobby Hutcherson release Enjoy the View, even when it was played at a loud level. In the bass the Duo sounded like a small to mid-sized floorstanding speaker, not a compact stand-mount. Pitches were fairly well defined, although the system leaned a bit toward the plummy side, but in a pleasant rather than distracting way. When pushed hard, the bass could get woolly, and the bottom-end transient performance wasn’t up to the same standard as the exemplary dynamic agility and transient quickness of the rest of the spectrum. Nonetheless, the Duo’s bass was musically satisfying and seldom called attention to itself. The Duo also played surprisingly loudly without strain. I never heard the woofer get into trouble when pushed hard; it’s possible that DSP prevents the woofer from being overdriven. Another outstanding characteristic was the Duo’s top-to-bottom coherence. The system sounded “of a piece,” with no discontinuities between the drivers and no part of the spectrum calling attention to itself.