AOM Logo October 1997

The Sonic Frontiers Line 1 Preamplifier
Of Sound Mind and Body

Andrew Chasin

To some degree, the proliferation of line-level only audio systems has rendered the preamplifier redundant. A system comprised of a single line-level source component with a variable output needs neither the source selection, volume control, nor phono equalization functions of a traditional preamplifier. Furthermore, the elimination of a preamplifier's circuitry, and its partnering pair of interconnects, results in a simpler, often sonically superior, reproduction chain. Why then does the preamplifier still find its way into so many high-end systems? Simply because most line-level sources, like CD players and tuners, don't contain variable outputs, and audiophiles whose systems are comprised of more than one source component generally prefer the convenience of a preamplifier's source-switching function over the drudgery of cable swapping. Of course, the volume control and source-switching functions of a preamplifier can be retained in a simpler device known as a passive attenuator, but this device's lack of a gain stage puts the onus on a source component to swing the output voltages necessary to drive the inputs of an amplifier through a set of interconnects. Many source components are simply not up to driving an amplifier's inputs directly, and require the extra gain supplied by an active line stage.

If you're like me, you'll find that an active line stage which, at a minimum, provides for volume attenuation and input switching, and supplies enough gain to drive an amplifier through relatively long runs of interconnects, is a necessary part of your audio system. Now, if such a device were available that just happened to contain balanced as well as unbalanced inputs and outputs, was supplied with a superbly engineered full-function remote control, and was filled with the finest audiophile-grade electrical components, yet rang it at a reasonable US$1995, wouldn't you be interested? I certainly was when I first heard of just such a device called the Line 1 preamplifier being brought to market by Canada's high-end wunderkind Sonic Frontiers. Sonic Frontiers' claim that the budget Line 1 outperformed their highly-regarded, but now-discontinued, top-of-the-line SFL-2 further piqued my interest, and I contacted them for a review sample.

The Line 1 Arrives - Finally!
My first request for the Line 1 came just after last September's Toronto Audio show. At that time, the Line series was simply vaporware and wasn't yet shipping to dealers, so I was put on the waiting list. And wait I did, although rather impatiently - audiophiles just hate waiting for new gear to arrive! A few months later, I was told by Sonic Frontiers' Chris Johnson that I had to wait a little longer as all available units were being shipped to dealers to satisfy customer requests. Customers? Get your priorities straight Chris! Compounding my frustration over the failure of the Line 1 to appear on my doorstep was the almost-ubiquitous appearance of the Line series at the Montreal Audio Show in March. Many good sounding systems in Montreal made use of one of Sonic Frontiers' new line stages. But Spring came and went, and no Line 1. Finally, in early July, I was informed that early customer demand had been met and a Line 1 was being shipped to Audiophilia for review. By this time, the Line 1's introductory price of US$1995 had given way to its permanent US$2495 price tag - not quite as price-competitive as before, but still quite reasonable for a high-end line stage with the Line 1's features, build quality and sonic lineage.

Line 1 Preamplifier The Sonic Frontiers Line 1 preamplifier replaces that company's well-regarded SFL-1 and SFL-1 Signature line stages. Cosmetically, the Line 1 closely resembles the SFT-1 transport and SFCD-1 CD player and sports Sonic Frontiers' now-familiar two-tone (black on silver or gold on silver), two-layer, aluminum on stainless steel faceplate.

The left side of the Line 1's front panel contains two rows of four solid stainless steel push buttons. These buttons select one of four single-ended or two balanced inputs, the buffered tape loop and the surround-sound processor loop. Volume and balance levels for each input (except the input dedicated to the surround-sound processor loop) may be saved in the Line 1's internal memory for later recall. Once saved, the volume and balance for a particular input are recalled whenever that input is selected. Saved levels are unaffected by loss of power to the Line 1. When switching between inputs (or out of mute state), the Line 1 slowly ramps the volume up to the saved setting, thus eliminating sudden, unexpected increases in volume - a nice touch.

The center of the front panel is occupied by a display window which is used to indicate the selected input, activation of the mute function, the selected phase angle, and the gain level (in dB) displayed digitally for each of the left and right channels. Volume levels may be set in 0.5dB increments through a very generous 191 steps from 0 to 95.5dB. Below the display window is a headphone jack incorporating the HeadRoom headphone processor, and five push-buttons: a phase reversal button, two buttons for adjusting left and right channel balance, a mode button (used to toggle between mono and stereo modes), and a button used to mute the Line 1's outputs. The front panel's right side sports a silky-smooth continuous-rotation, stainless steel volume control as well as a 'standby' switch. The latter switch is used to put the Line 1 into 'standby' mode in which the filaments in the Line 1's tube complement remain heated (avoiding the cold starts that contribute to shortened tube life) while plate voltage is maintained at about 10% of normal operating level. What? I didn't previously mention that the Line 1 contains tubes? But of course! Sonic Frontiers has never wavered in their commitment to the sonic superiority of the fire bottle, and have included a sextet of Sovtek 6922s in a cross-coupled, fully-differentially balanced configuration, at the heart of the Line 1. More on the Line 1's innards in a moment, but first a tour of its back side.

The Line 1's busy but well laid-out rear panel contains a bevy of inputs and outputs. Eight inputs, six single-ended on Tiffany-style gold-plated RCA jacks (two of which are dedicated to the surround-sound processor and tape loops) and two balanced inputs on XLR jacks, as well as two single-ended outputs and one balanced output are provided. For those wishing to use the Line 1 in a multi-room or home theater application, an I.R. jack and relay trigger are also provided. Rounding out the Line 1's rear panel are an IEC detachable power cord and a rocker-style on/off switch.

The Line 1's innards are housed in a chassis manufactured from plated 14 awg steel (painted with a scratch resistant powder-coat finish) which has been fully damped through the use of an internal layer of Soundcoat and the inclusion of four E.A.R. compliant feet. Although the Line 1's top plate provides for adequate ventilation, it does run quite hot and should be given ample air space above it.

Line 1 Innards Peering inside the Line 1 reveals that its superb build quality does not end at its exterior. The Line 1's 3 ½ ounce copper printed circuit boards are beautifully laid out and chock full of very high-quality audiophile-grade parts like Wima and MIT Multicap capacitors. The left side of the main circuit board contains the Line 1's gain stages, utilizing six Sovtek 6922 vacuum tubes which provide for 12dB of gain in single-ended mode and 18dB of gain balanced. This portion of the main circuit board contains a small "satellite" board which holds the popular HeadRoom headphone processor. The right side of the main board is occupied by the power supply circuitry, filter caps and toroidal power transformer; no less than fifteen regulated power supply stages are utilized in the Line 1. The power supply section is magnetically isolated from the rest of the main circuit board by a vertically-mounted magnetic shield. A separate shielded circuit board located just behind the front panel contains the Line 1's display logic, volume pot, and remote receiver circuitry.

Line 1 Remote Control The all-aluminum remote control supplied with the Line 1 is the most innovative and well-engineered of its kind to my knowledge. First off, it's round, which means it actually fits in the palm of your hand the way that all remotes should but never do. Second, its buttons, which duplicate all front panel functions, are so well laid out that after a few minutes of use you'll be able to find the one you want even in the dark - well, most of the time. Even though the commonly used buttons have tactile indicators, like a raised "dot" on the mute button and round depressions for the volume increase/decrease buttons, I still found myself pushing the wrong button from time to time during late-night lights-out listening sessions. Maybe the next version of the remote will feature internally back-lit buttons for us nocturnal listeners. Thankfully, lights-out listeners haven't been totally forgotten by Sonic Frontiers' engineers. Using the remote control's "DISP" button, the Line 1's display, which could prove a bit hard on the eyes in a dark room, can be either turned off or set to one of four brightness levels. Rounding out the remote (no pun intended), is a rubber O-ring which fits into a circular depression machined into its bottom. This prevents the aluminum bottom plate from scratching glass or wood furniture and allows the remote to be perched on inclined surfaces (like the arm of my Ikea listening chair) without crashing to the floor. Off-axis operation of the Line 1's remote was excellent. Only at extremely small angles of incidence (less than about 30 degrees) did the remote control and the receiver fail to shake hands.

Certainly no one can accuse Sonic Frontiers of cutting corners on the Line 1's build or parts quality. Inside and out, the Line 1 is superbly assembled and finished.

Setup and Operation
Sonic Frontiers has made setup of the Line 1 a breeze. They not only provide a Philips-head screwdriver for removing the top cover (in order to gain access to the tube sockets), but they also supply a set of white gloves for handling and installing the supplied tubes. Inclusion of a screwdriver is a nice touch - nothing would be more frustrating than anxiously unpacking your new Line 1 only to find out that you don't have the right type of screwdriver to remove the cover. While it might seem that the pair of supplied gloves is frivolous, there is a very practical reason for their inclusion. Handling a tube's glass envelope causes body oils to be deposited, which, when heated to a tube's high operating temperature, may weaken the envelope thus shortening tube life.

The Line 1 is also supplied with a very informative and well-written user's manual which provides clear instructions for installing the preamplifier's six tubes as well as detailed operational instructions for all of its functions.

Operation of the Line 1 is straightforward. The preamplifier is powered up using the rocker switch found on its rear panel. Once powered up, the Line 1 automatically enters 'standby' mode (indicated on the front panel by two pairs of three illuminated green LEDs). At this point, the 'standby' switch may be depressed causing the Line 1's mute function to be automatically engaged while its tube complement is brought up to full operating power. After a few seconds, the Line 1 automatically switches out of its muted state and is ready for normal operation. Switch in your favorite input, adjust the volume and you're ready to listen.

It's worth noting that the Line 1's very low output impedance (150 Ohms for its single-ended outputs and 300 Ohms for its balanced outputs) implies that it will easily drive long runs of interconnects and should form a synergistic partnership with the low input impedance of many solid-state amplifiers. Furthermore, the Line 1's direct-coupled output results in an output impedance which remains constant across the frequency spectrum.

The only operational glitch that marred an otherwise perfect record was a disconcerting "pop" heard through the loudspeakers whenever the mute or phase reversal functions were engaged or disengaged. While no tweeter damage resulted, this did prove to be annoying and was out of step with the Line 1's otherwise flawless operation.

One other minor problem that I encountered was a result of the Line 1's maximum single-ended input voltage of 4V. When using my Theta DS Pro Progeny DAC (whose output voltage of 4.5V is considerably higher than the industry standard 2V), I occasionally overloaded the Line 1's single-ended inputs, resulting in an audible "tick" heard through the loudspeakers. Fortunately, a brief consultation with the terrific folks at Theta Digital, and a few hours on the operating table at a local Theta dealer, brought the output level of the Progeny down to a more moderate 2V - problem solved. Those using the Line 1's balanced inputs, and/or a DAC whose output voltage is less than 4V, should not encounter this problem.

Associated Components

Digital: Theta Data Basic II Transport, Theta DS Pro Progeny and Assemblage DAC-2 DACs
Preamplifiers: Sonic Frontiers Line 1, Conrad-Johnson Premier II
Amplifiers: Aragon 2004 Mk.II, Celeste Moon W-5
Loudspeakers: ProAc Studio 150, ProAc Response One SC, Meadowlark Kestrel
Cables: Transparent Audio MusicLink Plus, Music Wave Plus, Audio Magic Presto, WireWorld Oasis II, XLO Type 4 digital, D Lin Audio Silver Bullets 4.0
Accessories: Target equipment rack and power amplifier stand, Blu-Tak adhesive, CD Stoplight, 15A dedicated AC outlets, Echo Busters room treatment products.

The first thing that struck me about the sound of the Sonic Frontiers Line 1 preamplifier was how un-tubey it was. The Line 1 added no artificial warmth to the midrange, didn't roll-off the top-end and didn't bloat or short-change the low frequencies the way that some classic tube preamplifiers do. If you're looking for a preamplifier which will add an artificial sense of warmth or body to the sound of recorded music, then look elsewhere - transparency and neutrality, rather than euphonic colorations, are what the Line 1 is about. I would caution those who gravitate towards the richer, warmer house-sounds of, say, Jadis or Conrad-Johnson, to audition the Line 1 carefully to ensure that its character suits their musical tastes. I, for one, preferred the near tonally-neutral balance of the Line 1 to the sonic editorializing of many well-known tube products.

In fact, the Line 1 had very little sonic signature of its own, and allowed the unique sound of each recording and recorded venue to reach the listener unscathed. The Line 1 faithfully represented the sonic superiority of good recordings and laid to bear the shortcomings of lesser ones. To my way of thinking, such a product is far more desirable than one with a purposefully-tuned tonal balance which lends a sense of palatability to inferior recordings at the expense of superior ones.

Of course a neutral tonal balance is but one piece of the sonic pie. Dynamics, and in particular macrodynamics, are the life-blood of much symphonic music, and their faithful reproduction is key. Sadly, compression of macrodynamics is one of the qualities of electronically-reproduced music that all too often gives it away as such. Macrodynamic compression manifests itself aurally as an artificially-imposed ceiling on volume - the refusal of an audio system to elevate its output from ff to fff, for example. Given the current state of the art, it is rare indeed for any audio system, regardless of its price, to reproduce macrodynamics with concert-hall realism (rare but not impossible, if my recent exposure to the Waveform Mach 17 loudspeaker is any indication). An audio component which elevates a system to new heights of dynamic realism deserves high praise - such was the case with the Line 1 preamplifier. When the music called for monumental swells of volume, such as the build-up to, and realization of, the orchestral climaxes of Shostakovich's Symphony No.9 (Vladimir Ashkenazy/Royal Philharmonic Orchestra, London 430 227-2) or Beethoven's Symphony No. 7 (Carlos Kleiber/Wiener Philharmoniker/DG 447 400-2), the Line 1 delivered, without the strain, glare, loss of transparency or collapse of soundstage heard with lesser preamplifiers. If the Line 1 had a limit on its dynamic capabilities, I never managed to encounter it.

I was further impressed by the Line 1's ability to unearth low-level recorded detail and weave it seamlessly into the musical tapestry. While I don't care to be privy to every biological utterance captured during a recording session (need I say more?), the Line 1's rendering of subtle environmental cues (such as a hall's ambient acoustic signature), the slightest movement of instrumentalists in their chairs, or a closely-miked wind player's inhalations of breath, significantly heightened the illusion of reality. The Line 1's very low noise floor no doubt contributed to its superb low-level resolution. Even with the gain set to its maximum level, the Line 1 exhibited a relatively small amount of audible tube rush, and proved to be one of the quietest tube preamplifiers to grace my reference system (at least as quiet as the considerably more expensive Audio Research LS-15).

In recent months I have made extensive use of Christian McBride's Gettin' To It (Verve 314 523 989-2) for gettin' to the heart of a component's low frequency performance. Two tracks in particular, Splanky and Night Train, present a real challenge to most audio components. Splanky features the double bass trio of Christian McBride, Ray Brown and Milt Hinton, and is a great test of a component's low end resolution and articulation. The closely-miked Night Train is solo McBride at his very best, as he ably demonstrates the full-range and lovely tonality of his instrument. Listening to these tracks through the Line 1 was a highly pleasurable experience. The Sonic Frontiers line stage exhibited a wonderfully extended, punchy, and articulate bottom-end that belied its vacuum tube origin. In partnership with the iron-fisted Celeste Moon W-5 solid-state amplifier (review forthcoming), the Line 1 set a new standard for bass performance in my listening room, extending deeper and tighter than anything which preceded its arrival. Through the Conrad-Johnson Premier II (my long-term, but somewhat long in the tooth reference), the lowest reaches of David Piltch's acoustic bass work on Holly Cole's Temptation were fuzzy and frustratingly indistinct. Switching to the Line 1 snapped the bass into focus and made it easy to follow Piltch's descent down the frequency scale to the lower limits of his instrument. Not only did the Line 1 excel at bass on a large scale (such as the powerful bass drum strokes captured on Telarc's superb recording of Rachmaninoff's Symphonic Dances with David Zinman and The Baltimore Symphony Orchestra, Telarc CD-80331), but it was quite adept at presenting the more delicate low-frequency soundings of the pianissimo double bass passages of Shostakovich's Symphony No. 9. Further comparisons between the Line 1 and the Premier II revealed the bottom-end of the latter preamplifier to be loose and lacking in extension and definition. The Premier II is classic tube sound personified, a sound to which the Line 1 clearly does not aspire.

The midrange presented by the Line 1 had a welcome absence of grain and coarseness. One recording which I have found to be particularly telling of a component's midrange performance is Cassandra Wilson's New Moon Daughter (Blue Note 7243 8 32861 2 6). In particular, the sound of Wilson's voice heard on her cover of U2's Love Is Blindness has a tendency to sound gritty and course if the reproducing electronics err even slightly in the upper reaches of her vocal range. Through the Line 1, Wilson's voice was the antithesis of coarse and grainy, instead sounding smooth, liquid and natural. The same could be said of Loreena McKennittt's voice as heard on the superb The Mask and Mirror (WEA CD-95296). The upper reaches of Ms. McKennitt's relatively high-pitched voice (best characterized as Kate Bush-meets-Peter Gabriel-meets-Enya), possessed great clarity and were detailed yet unfatiguing, even when played back at high levels. The sound of a massed chorus (not a sound easily replicated by electronic components) was well served by the Line 1. The choral backing of Loreena McKennitt's The Mystic's Dream from The Mask and Mirror sounded rich, three-dimensional and beautifully layered within the soundstage. Once again, midrange grain and grit were not in the Line 1's sonic vocabulary.

While the Line 1's lack of grain through the midrange proved most appealing, it was this very range of frequencies that exhibited a slight chalky, dry texture that could be somewhat ameliorated by appropriate choice of cables (D Lin Audio's Silver Bullet 4.0s proved a particularly synergistic match) but never entirely disappeared. This particular characteristic was apparent on a variety of female vocal and violin recordings and, although minor in an absolute sense, was the only real deviation from neutrality that was consistently identifiable. Hey, Sonic Frontiers has to give you some reason to spring for the Line 2 or 3!

Not much in the way of criticism could be leveled at the Line 1's beautifully filigreed and extended treble. The Line 1 did a wonderful job of communicating the inventiveness and subtle shadings of Steve Davis' stellar cymbal work on The Lynne Arriale Trio's The Eyes Have It (DMP CD-502). The sound of the bell of Davis' ride cymbal rang out with startling clarity. The high, massed violins of Beethoven's Symphony No. 7 sounded smooth and velvety, without the hardness or glare heard with the Conrad-Johnson Premier II. Coupled with the Line 1's smooth, refined top-end were fast high-frequency transients which sounded neither etched, hyped nor synthetic. Steve Davis' cymbal splashes lit up the listening room like shooting stars against the deep black of the night sky. The percussive effects used to perfection in Debussy's Images pour orchestre (James Levine/Berlin Philharmonic, Sony SK53284), and the cow bell in the closing bars of Donald Fagan's New Frontier from The Nightfly (Warner Bros. CD-23696), sounded shockingly realistic; so much so that they actually startled me on occasion!

As far as staging and imaging are concerned, the Line 1 was hard to fault and was competitive with the best I've heard. Soundstage width and depth were excellent and images were drawn within that soundstage with precision - assuming, of course, that a recording managed to capture that type of information in the first place. A recording which does manage that feat is Loreena McKennitt's The Mask and Mirror (mastered by Bob Ludwig at Gateway - does that guy ever produce a clunker?). The Victoria Chorus heard on The Mystic's Dream from this disc, was set realistically back in the soundstage and was nicely layered from front to back. A three-dimensional soundstage, as well as sharply focused images, was also readily apparent on the RIAS-KAMMERCHOR's award-winning traversal of Brahms' sacred choral music (Harmonia Mundi HMC 901591). The spatial locations of individual choir members were easily identifiable, adding a heightened sense of tangibility to the proceedings.

I don't want to give the impression that the Line 1 only excelled at individual aspects of musical reproduction at the expense of presenting a coherent sonic whole - nothing could be further from the truth. The Line 1 was most definitely the sum of its parts and presented a wonderfully coherent musical picture that was a pleasure to behold.

If you got the impression that I found the Sonic Frontiers Line 1 preamplifier to be a highly musical device, then I've been successful in conveying my thoughts. Near tonal neutrality, tight, extended bass, a smooth, grain-free midrange and a detailed, extended treble are all features of this fine product. Throw in the ability to reproduce a wide, deep soundstage upon which sharply drawn, tangible images are placed, the ability to serve up the music on a bed of virtual quietude, and, most importantly, the ability to simply let the musical event unfold without its obvious intervention, and you've got yourself a recipe for musical rapture. And if that weren't enough, the Line 1 boasts terrific build and parts quality (with a commensurate five year warranty - 1 year on the tubes!), enough features to fend off obsolescence for the foreseeable future, and some of the finest ergonomics in the business. Could it possibly be any better than this? Well, since you asked, a touch more warmth through the midrange might be nice, the remote could be back-lit for us lights-out types, and the availability of an optional internal phono stage would be great for those of us who still spin the black circle. But I nit-pick. The fact is, if you're looking to build an audio system around a high-quality, full-featured line stage which can be had at a reasonable price, I can think of few that would be a better choice than the Sonic Frontiers Line 1. Very highly recommended.

Line 1 Preamplifier
Manufactured by Sonic Frontiers Inc.
2790 Brighton Road, Oakville, Ontario, Canada, L6H 5T4
Phone: (905) 829-3838, Fax: (905) 829-3033
Price: US$2495.00
email:, web:
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