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Unison Research S6 Black Edition integrated amplifier Page 2

Setup
To isolate the amp from resonance nasties and rowdy FedEx trucks rumbling down my well-worn Greenwich Village block, I placed an Aptitlig bamboo cutting board underneath the S6 Black Edition. This, along with Norman Varney's EVPs (the best isolation pucks I've found for resonance control and noise reduction) placed under the Aptitlig, provided vibration isolation. To evaluate the S6 Black's internal DAC, I connected my Tascam CD 200iL CD player via a single Triode Wire Labs Spirit RCA cable running from the CD player's coax output to the S6's S/PDIF input.

Biasing the KT77 tubes…

Unison Research S6 Black Edition integrated amplifier Specifications

Sidebar 1: Specifications

Description: Two-channel, tubed class-A, Ultralinear integrated amplifier. Tube complement: six KT77 Gold Lion; two 12AX7/ECC83 Gold Lion. Inputs: four single-ended (RCA), USB, S/PDIF, TosLink. Outputs: Two pairs loudspeaker output terminals, subwoofer (RCA). Power output: 40Wpc into 6 ohms (14.75dBW) specified at 5% THD. Frequency range: 15Hz–30kHz. THD+N: 0.5% at 1W. Total gain (from line inputs): 35dB. Input impedance: 50k ohms. Max. power consumption: 265VA.
Dimensions: 13.75" (349mm) wide × 17" (4312mm) deep × 8" (203mm) high. Weight: 55lb (25kg).
…

Unison Research S6 Black Edition integrated amplifier Associated Equipment

Sidebar 2: Associated Equipment

Analog sources: Thorens TD 124 with Korf TA-SF9R tonearm/HS-A02 Ceramic Headshell. Ortofon 2M LVB 50, Kuzma CAR-30 phono cartridges.
Digital source: Tascam CD-200 iL CD player.
Preamplifiers: Tavish Audio Design Adagio (phono).
Loudspeakers: DeVore Fidelity Super Nine, Volti Audio Lucera, Voxativ Ampeggio 2024.
Cables: Interconnects: AudioQuest Pegasus and Firebird, Triode Wire Labs Spirit II (RCA). Speaker: AudioQuest William Tell Zero (10'). AC: AudioQuest NRG Z.
Accessories: Pro-Ject VC-S2 ALU, HumminGuru record cleaning machines;…

Unison Research S6 Black Edition integrated amplifier Measurements

Sidebar 3: Measurements

I performed a full set of measurements on the Unison Research S6 Black Edition using my Audio Precision SYS2722 system. I carefully installed the tubes and after leaving the amplifier powered up for 30 minutes, checked that the bias for each of the six KT77 output tubes was correctly set. I rechecked the bias every 30 minutes during the testing.

Looking first at the S6 Black Edition's unbalanced line inputs, the input impedance measured 39k ohms at 20Hz and 1kHz and 36k ohms at 20kHz. The amplifier inverted absolute polarity at both the loudspeaker and…

Unison Research S6 Black Edition integrated amplifier More Measurements

To examine the performance of the S6 Black Edition's digital inputs, I used the coaxial and optical S/PDIF inputs—the optical input only accepted data sampled at rates up to 96kHz—and USB data sourced from my MacBook Pro. The USB Prober utility identified the S6 Black Edition as "UNISON USB DAC 2" from "UNISON RESEARCH," with the serial number string "0 (none)," and indicated that the USB port operated in the optimal isochronous asynchronous mode. Apple's AudioMIDI utility showed that the Unison Research accepted 16-bit and 32-bit integer data via USB sampled at all rates from 44.1kHz to…

Room Correction, Swiss Precision, and Serious Scale: Von Schweikert, WestminsterLab, Rockna, LUMIN

New York–based dealer New Life Audio teamed up with California distributor Hear This—representing WestminsterLab and Von Schweikert Audio—to build a system around those two brands. On a Bach Violin Concerto, played with characteristic sweetness—if not period authenticity—by Belgian violinist Arthur Grumiaux, both tone and texture came through with striking fidelity.

At my request, we transitioned from Grumiaux in 16-bit/44.1kHz to Isabelle Faust in 24-bit/96kHz. I didn't scribble down what we played, but I suspect it was either the Ligeti or Britten Violin Concerto. Colors and textures…

Pearl Acoustics: Luster at the End of the Hall

“Do you know where the room with Pearl Acoustics Sibelius loudspeakers is?” That question, which greeted Jim Austin and me as we navigated the stairs, grew increasingly common as AXPONA unfolded.

Pearl wasn’t listed in the official show guide, but word of mouth made the English company impossible to ignore. Its room, tucked away at one end of the fourth floor, became a destination—helped, perhaps, by the firm’s devoted YouTube following. While we were setting up for our video shoot, a Pearl owner popped in to say hello. I believe he was an oboist with the Metropolitan Opera Orchestra:…

Wattson’s Madison Amplifier Debuts with CH Precision DNA, Magico Brawn

At Munich High End 2024, my biggest discovery was Switzerland’s Wattson Audio. It’s easy to hear a sonic kinship between Wattson and its new owner, CH Precision—an affinity that helped explain CH’s acquisition of the company last year.

At AXPONA, Wattson introduced its new Madison amplifier ($6495), a fully discrete, class-AB, dual-mono design rated at 50Wpc into 8 ohms. Configurable for stereo, mono, or biamp use, it was paired with the Madison LE Streamer ($4995), launched in 2023.

Kevin Wolff, CH Precision’s director of global sales and US distributor for Wattson Audio, and…

Friends with (Sonic) Benefits: Stenheim, VTL, Grand Prix, Kuzma, Nordost, and dCS

Stenheim, VTL, and Nordost returned as AXPONA system partners, joined this year by several notable additions. The analog front end featured Grand Prix Audio’s Monaco 3.0 turntable ($56,250) with Fuel Station battery power supply ($15,250), Kuzma’s Safir 9 tonearm ($23,140), and a Lyra Etna cartridge ($8995). Nordost showcased four rare Odin Gold power cords ($43,999), alongside its familiar Odin 2 and Valhalla 2 cables and a broad range of accessories. Digital duties had shifted from last year’s dCS Rossini Apex to the full Vivaldi Apex stack: DAC ($46,500), Upsampler ($27,000), and Master…

Analog Corner #225: Why, in 2014, Does Vinyl Continue to Grow?

Michael Fremer advocating vinyl and analog on MTV in 1993.

Vinyl sales in America rose 30% in 2013, according to Nielsen SoundScan, which keeps a tally of recorded media sales. Because Nielsen SoundScan only skims the surface of the record retailing picture, missing considerable "nook and cranny" sales, the real number is probably far greater. The SoundScan numbers also omit sales of used vinyl, which are considerable.

By the time you read this, I will have posted on Analogplanet.com worldwide record-pressing totals, from information I've obtained direct from the pressing plants.…