One very cool feature is the 160M's tube-hours counter, just below the three toggles. I checked it frequently while completing the 400–600 hour break-in process that ARC had begun. Many makers of tube amps caution against turning on their amps when they're not connected to speakers. Although Dave Gordon had told me that I could break in the 160Ms' tubes without connecting the amps to my speakers, ARC later sent me two huge, heavy brass resistors. I connected these to the 160Ms' speaker terminals, to ensure that break-in would occur evenly.
Setup
I positioned the 160Ms on Grand Prix Audio Monaco amp stands equipped with Grand Prix's new donut dampers, provisionally named the Visco Voids. Though their name may invoke images of the ominous black hole that gobbled up the Starship Enterprise, my limited experience of the Visco Voids suggests that they're now Grand Prix's best dampers for controlling resonance and ensuring tight bass. Nordost Odin 2 balanced interconnects (XLR) linked the 160Ms to either the dCS Vivaldi DAC or ARC's REF 6 preamp; in the latter case, single-ended Nordost Odin 2s (RCA) connected the REF 6 to the Vivaldi.
The 160M has separate speaker terminals for 4, 8, and 16 ohm loads. Given that the Wilson Audio Alexia 2 has a nominal impedance of 4 ohms, my first inclination was to use the 160Ms' 4 ohm taps. But when Gordon visited, he made a point of hooking up the Alexias to the amps' 8 ohm taps, insisting that all 4 ohm Wilson speakers sound best through the 8 ohm taps of ARC amps.
Wilson's Peter McGrath insisted, in a subsequent exchange, that, indeed, "Every Audio Research amp we've used with every Wilson speaker we've made has sounded best on the 8 ohm tap, without exception. The minute you'd go to the 4 ohm tap, the bass would become thicker, woollier, or out of control." It never occurred to me until after I'd sent the amps on to John Atkinson to be measured that, regardless of those cautions from ARC and Wilson, I should have tried the 160Ms' 4 and 16 ohm taps to confirm their findings for myself.
Listening
From the get-go, music through the Reference 160Ms elicited a loud "Whoa!" In short order, all my expectations of what I'd thought was ARC's house sound—and the sound of most tubed gear—went out the window. The first track I played, via the dCS Paganini transport, was Antonio Bertali's sometimes riotous Ciaconna for Violin, Keyboard, and Chitarrone, from violinist Rachel Podger's Perla Barocca: Early Italian Masterpieces (SACD/CD/DSD64, Channel Classics 36014). While I'd heard "blacker" backgrounds, the distinctive tone of Podger's gut-strung period instrument was there to savor in full. Undertones and overtones were present in equal measure, and the piquant sounds of Podger's plucked strings contrasted beautifully with the warmth of Marcin Swiatkiewicz's pump organ and Daniele Caminiti's theorbo.
"Simply delicious," I wrote in my notes. I especially noticed a musical transition about four minutes in, when the violin, guitar, and theorbo take over from the bubbling organ. When instrumental lines doubled, the sound was just yummy. When everybody revved up at once and the intensity increased, hard-to-distinguish details and sonorities emerged with clarity.
Next came Vadim Gluzman performing the Brahms Violin Concerto, with the Luzerne Symphony Orchestra under James Gaffigan (SACD/CD, BIS 2172). I reveled in the gorgeous colors of Gluzman's instrument, the soaring freedom of his playing, the living quality of this performance. When in reviewer mode I often listen to only snippets of long works, but Gluzman's violin sang so beautifully that I couldn't turn it off. What a heavenly performance!
Lulled by the beauty, I also took in the start of Brahms's Violin Sonata 1, in which Gluzman is joined by his wife, pianist Angela Yoffe. Her piano sounded gorgeous, and was presented in correct perspective to the violin.
I upped the ante and plumbed the depths with Mahler's Symphony 2, as performed by Iván Fischer and the Budapest Festival Orchestra (SACD/CD, Channel Classics CCS SA 23506). At the beginning of the first movement, when the cellos and double basses double an octave apart, they sounded natural, their colors fully fleshed out. At the first raucous cymbal crash, my eyes opened wide. And when Mahler transitions from darkness to light, it felt as if the sun was finally coming out, however briefly (hey, it's Mahler).
Over the next 24 hours I listened to some favorite test tracks whose sounds I've heard through more combinations of audio gear than Donald Trump has issued tweets: the title track of Sarah Vaughan and the Count Basie Orchestra's Send in the Clowns, an incomparable rendition of Sondheim's song in a 1981 studio recording (Pablo/JVC-XRCD VICJ-60246); lyric soprano Elly Ameling's singing Schubert's "Die Sterne," with pianist Dalton Baldwin, from The Artistry of Elly Ameling (CD, Philips 473-4512); Murray Perahia's performance, on piano, of Handel's joyous Harpsichord Suite in E, HWV 430 (CD, Sony Classical 62785); and soprano Carolyn Sampson's and pianist Joseph Middleton's superb performance of Purcell's song "Sweeter than Roses," from her recital disc Fleurs (SACD/CD, BIS 2102). They all sounded exceptional.
Via USB sticks inserted in the dCS Network Bridge, I turned to high-resolution files of recordings I've reviewed for Stereophile.com: Semyon Bychkov and the Vienna Philharmonic's performance of Schmidt's Symphony 2 (24-bit/48kHz WAV, Sony Classical 88985355522/Primephonic); the marvelous finale of Debussy's Sonata for Flute, Viola, and Harp, respectively performed by Emmanuel Pahud, Gérard Caussé, and Marie-Pierre Langlamet and recorded in a naturally resonant acoustic (24/96 WAV, Erato 565142); the beginning of Mahler's expansive Symphony 3, in the superbly recorded performance by Iván Fischer and the Budapest Festival Orchestra (DSD128, Channel Classics CCS SA 38817/NativeDSD); "Electrified II," from Yello's Toy (24/48 WAV, Polydor 4782160/HDtracks); and more. As track followed track, what I heard was consistent: sound so natural, full-range, and beautiful that I was totally won over.
Enter the Audio Research REF 6 preamplifier
To help move amps and offer a second opinion as I compared the Reference 160Ms with the Dan D'Agostino Master Systems Progression monoblocks, I welcomed to my listening room my physician and percussionist friend, Gary Forbes. Bless his heart, Gary brought over two non-classical CDs. From old-time American music specialist Catherine Russell's irresistible Bring It Back (Jazz Village 579001) we chose Koehler and Arlen's fabulous "Public Melody Number One," and our track of choice from Gregory Porter's Be Good (Motéma 75) was "Real Good Hands." For major contrast on all levels, we returned to my DSD128 files of Mahler's Symphony 3. While, with the Mahler, the Progressions granted more natural weight to bass and percussion, more air and complexity to timbres, and set a wider and more transparent soundstage farther back, the 160Ms sounded excellent in their own right. But when we added the REF 6 preamp—I turned the Vivaldi DAC's volume all the way up to unity gain and used the REF 6 to control volume—the sound of the 160Ms got even better.
Porter's "Real Good Hands" presented the first of many "wow" moments, as Gary and I marveled at the enhanced air and depth, and the increased beauty of the midrange. Gary was especially struck by the additional air and space around the saxophone. Russell's singing, in turn, unquestionably swung more and was even more engaging. The sound of the horns was to die for, and bass lines were well defined. In the Mahler, the depth and beauty of the midrange were notably enhanced: the deep bass was weightier and more in control, and the sound remained "of one piece," with no timbre or frequency range over-emphasized.
"The massed strings and decay in the room sound more natural to my ears," said Gary. "The horns seem part of the ensemble rather than sticking out, and the solo violin has more of a sense of wood." I noted the extra emotional impact made by Mahler's radiant transition from darkness to light, and an increase in natural overtones. Everything sounded more substantial, and gained in emotional impact.
Granted, the Progressions were better at conveying soundstage depth and width, image weight, and the ability to let me hear the sides of the hall. Though I loved the Progressions most without the REF 6 in the chain, during a later comparison session I enjoyed how the REF 6 enhanced some of the Pass Labs XA200.8s' most endearing qualities. Regardless, the bloom we heard with the ARC pairing of Reference 160Ms and REF 6 sounded heavenly to our ears. Forget the oft-invoked "It's all good"—what we heard was much better than that.
For all my listening from that point on, I stuck with the synergistic combo of REF 6 and Reference 160M. When I compared the 160Ms' Ultralinear and Triode modes, I was surprised at how musical the amps sounded feeding the Alexia 2s the 75Wpc of Triode mode. Nonetheless, Triode sounded warmer than neutral, especially around the edges of notes. Drums sounded a little flatter, rapid timpani rolls were a mite smudged, and colors and images were less naturally defined. Instead of major exclamation points, Triode delivered lots of warm'n'fuzzies. While I could certainly hear why many audiophiles, especially with smaller-scale material or with smaller speakers, will be seduced by the sound of Triode mode, I remain an Ultralinear man.
I did lots more listening as I reviewed multiple recordings. No matter what I played, my love for the Reference 160Ms remained constant.
The Wrap
Of all the power amplifiers, integrated amplifiers, and pre-power combinations to have spent time in my reference system, the pairing of Audio Research's tubed Reference 160M monoblocks and REF 6 preamplifier stands out as having sounded the most musically neutral and natural. Other components may offer more warmth and glow, or wider soundstages, or greater dynamic contrast, or more bass slam, transparency, and detail—but there was an inherent rightness to the sound of this supremely musical ARC pairing that puts it in a class by itself. Since hearing the Reference 160Ms and REF 6 together, all of my preconceptions about the sound of tubed equipment have gone out the window. While choosing an amplifier will always be based upon many factors—economic means, personal taste, and the willingness to monitor and occasionally replace tubes among them—I'm convinced that the Reference 160M will find a home on many a solar- or wind-powered desert island. It's that good.
I positioned the 160Ms on Grand Prix Audio Monaco amp stands equipped with Grand Prix's new donut dampers, provisionally named the Visco Voids. Though their name may invoke images of the ominous black hole that gobbled up the Starship Enterprise, my limited experience of the Visco Voids suggests that they're now Grand Prix's best dampers for controlling resonance and ensuring tight bass. Nordost Odin 2 balanced interconnects (XLR) linked the 160Ms to either the dCS Vivaldi DAC or ARC's REF 6 preamp; in the latter case, single-ended Nordost Odin 2s (RCA) connected the REF 6 to the Vivaldi.
The 160M has separate speaker terminals for 4, 8, and 16 ohm loads. Given that the Wilson Audio Alexia 2 has a nominal impedance of 4 ohms, my first inclination was to use the 160Ms' 4 ohm taps. But when Gordon visited, he made a point of hooking up the Alexias to the amps' 8 ohm taps, insisting that all 4 ohm Wilson speakers sound best through the 8 ohm taps of ARC amps.
From the get-go, music through the Reference 160Ms elicited a loud "Whoa!" In short order, all my expectations of what I'd thought was ARC's house sound—and the sound of most tubed gear—went out the window. The first track I played, via the dCS Paganini transport, was Antonio Bertali's sometimes riotous Ciaconna for Violin, Keyboard, and Chitarrone, from violinist Rachel Podger's Perla Barocca: Early Italian Masterpieces (SACD/CD/DSD64, Channel Classics 36014). While I'd heard "blacker" backgrounds, the distinctive tone of Podger's gut-strung period instrument was there to savor in full. Undertones and overtones were present in equal measure, and the piquant sounds of Podger's plucked strings contrasted beautifully with the warmth of Marcin Swiatkiewicz's pump organ and Daniele Caminiti's theorbo.
Lulled by the beauty, I also took in the start of Brahms's Violin Sonata 1, in which Gluzman is joined by his wife, pianist Angela Yoffe. Her piano sounded gorgeous, and was presented in correct perspective to the violin.
To help move amps and offer a second opinion as I compared the Reference 160Ms with the Dan D'Agostino Master Systems Progression monoblocks, I welcomed to my listening room my physician and percussionist friend, Gary Forbes. Bless his heart, Gary brought over two non-classical CDs. From old-time American music specialist Catherine Russell's irresistible Bring It Back (Jazz Village 579001) we chose Koehler and Arlen's fabulous "Public Melody Number One," and our track of choice from Gregory Porter's Be Good (Motéma 75) was "Real Good Hands." For major contrast on all levels, we returned to my DSD128 files of Mahler's Symphony 3. While, with the Mahler, the Progressions granted more natural weight to bass and percussion, more air and complexity to timbres, and set a wider and more transparent soundstage farther back, the 160Ms sounded excellent in their own right. But when we added the REF 6 preamp—I turned the Vivaldi DAC's volume all the way up to unity gain and used the REF 6 to control volume—the sound of the 160Ms got even better.
Porter's "Real Good Hands" presented the first of many "wow" moments, as Gary and I marveled at the enhanced air and depth, and the increased beauty of the midrange. Gary was especially struck by the additional air and space around the saxophone. Russell's singing, in turn, unquestionably swung more and was even more engaging. The sound of the horns was to die for, and bass lines were well defined. In the Mahler, the depth and beauty of the midrange were notably enhanced: the deep bass was weightier and more in control, and the sound remained "of one piece," with no timbre or frequency range over-emphasized.
Of all the power amplifiers, integrated amplifiers, and pre-power combinations to have spent time in my reference system, the pairing of Audio Research's tubed Reference 160M monoblocks and REF 6 preamplifier stands out as having sounded the most musically neutral and natural. Other components may offer more warmth and glow, or wider soundstages, or greater dynamic contrast, or more bass slam, transparency, and detail—but there was an inherent rightness to the sound of this supremely musical ARC pairing that puts it in a class by itself. Since hearing the Reference 160Ms and REF 6 together, all of my preconceptions about the sound of tubed equipment have gone out the window. While choosing an amplifier will always be based upon many factors—economic means, personal taste, and the willingness to monitor and occasionally replace tubes among them—I'm convinced that the Reference 160M will find a home on many a solar- or wind-powered desert island. It's that good.
