I'm going to cheat a little here. My comments on the Sonic Frontiers Power 3 monoblock power amplifier2 are a Follow-Up to Brian Darnkroger’s review in the April 2000 issue, but the $4999 SF Line 3 preamplifier has not been given a full review in these pages. I offer my observations of amp and preamp, separately and as a team, because my feelings about the two differ significantly from Brian’s.

When I reviewed the $3299 Line 2 (December 1997, Vol.20 No.12), I was completely won over by it and was somewhat disappointed when, in response to my pleading for its return, I got a spanking new Line 3 instead! I wasn’t asking for more, and, at the time, didn’t think I wanted more.

Cosmetically and operationally, all of Sonic Frontiers’ Line-series preamps are identical, including that great remote control, and my review of the Line 2 and MK’s review of the Line 1 (Vol.20 No.11) cover that story. The SF Line preamps differ in the sophistication with which the fully balanced design is executed and, more obvious to the eye, the size and complexity of their power supplies. The Line 1 has an onboard power supply with 15 stages of regulation, the Line 2 has a small (but heavy) external power supply with 19 stages of regulation, and the Line 3 has a full-sized and very heavy external supply with 26 regulators, no fewer than eight of them of the high-voltage shunt type.

The Line 3 has three power transformers/raw supplies for the two audio channels and for the non-audio functions (display, control logic, etc.) so that all the audio circuits are isolated from the housekeeping functions. Each phase of each supply is provided with a C-L-C pi filter consisting of a 20µF Solen cap, a potted 2H inductor, and a 56µF Solen cap for excellent CMRR and separation, as well as ripple rejection and fast response to transient demands. Powerup is sequenced so that filaments are turned on first, followed by high voltage, and all high-voltage, supplies are shut down in the Standby mode. These measures reduce stress and prolong tube life.

Inside the main chassis, the 6-tube (all 6DJ8/6922) Line 1 and 2 appear somewhat similar, but the Line 2 is endowed with a more generous layout and upgraded components because there is no internal power supply. The 10-tube, 65-lb Line 3 is much more complex and elaborate, with component selections that go beyond compulsiveness and border on paranoia. Even the printed circuit boards are damped and isolated! Balanced and single-ended sources are fed via input resistors and input selection relays to the Line 3’s dual CS3310 volume controllers with differential amps (one 6922 per channel) on their outputs. SF says that this circuit arrangement offers better sound than earlier designs based on passive four-gang attenuators.

The cathode-follower output stage consists of two dual triodes per signal phase per channel, for a total of eight 6922s! One triode half of each 6922 is paralleled with that of another 6922 for low output impedance, while the second half of both serves as a paralleled constant current source. In addition, a pair of 6U8As regulates AC bias of the input stage and serves as an error amp to sense and correct phase balance in the output stage. DC servos are used around the output stage and no output coupling capacitor is used.

This results in a very low output impedance, especially for a tube preamp: 45 ohms single-ended, 90 ohms balanced.

But given that I said – in print, no less –1 couldn’t find any shortcomings in the Line 2!,” why even bother with the Line 3? Because the Line 3 corrects shortcomings of the Line 2 that are so minor that they are apparent only when removed. The two preamps share an overall balance and presentation that I continue to characterize as confoundingly neutral. That accounts for my inability to provide a lengthy subjective description, and for Brian’s wondering (about the Line 2, April 2000, p.101) diat,,ies odd that it doesn’t evoke a stronger emotional response. Is it because it’s so neutral ... or is it that it... is missing something that we don’t necessarily notice?” Like the Line 2, the Line 3 is not an exciting preamp, it’s merely exact. The Line 3 firms up the Line 2’s mid and extreme bass and removes the residual traces of grain throughout the spectrum. The Line 3 gains authority the longer one listens, and has become my reference tool for assessing other components.

I don’t share Brian’s expressed tolerance for small “errors to the warm, liquid side”... I like things tight and clean.

The Power 2 power amplifier sat in my listening room for more than a year and presented me with a conundrum similar to Brian’s with the Line 2. Over that time, and however much I resisted the prospect, I ended up choosing it – over every other amp and with almost every speaker for enjoying music. Sure, the Bryston 7B-STs had more slam and punch, the SimAudio Moon W-5 was more powerful and just as smooth, and the McCormack DNA-1 had more sparkle and fife. But I hooked up the Power 2 whenever I just wanted to listen to music. By common practice, it became my reference. ies not perfect, but the softness of the bass and its tendency to seem a bit mellow were acceptable in the context of its overall integrity of sound.

So even before I had a chance to read BD’s review of the Sonic Frontiers Power 3 monoblock amplifiers, I arranged to buy the review pair. Surely, the Power 3 would retain all of the characteristics of the Power 2 that I so prized, and the scaled-up monoblocks just might correct the 2’s lapses. The Power 3s were still on their circuitous trip from BD to TJN (for testing) to Sonic Frontiers (for a checkup and retubing) to me, when I saw BD’s review in print and read, with horror, that “These amps don’t rock.” Had Ijust blowri it?

I need not go through all the details of the Power 3, because I can find nothing to dispute in Brian’s observations: I heard the same things. Moreover, I think he and I would agree that we don’t want a component that sounds “good” or “great,” but one that doesn’t “sound” at all. Still, one needs only to glance at the comments that Brian and I have made over the years about Sonic Frontiers components (encapsulated in the “Recommended Components” listings for the Line 2 and Power 2 in the April Stereophile) to predict that we would not have the same emotional response to the Power 3. In addition to our having different heads and hearts, our system contexts (sources, speakers, rooms) are quite different, and our musical interests only partly overlap. Finally, I don’t share Brian’s expressed tolerance for small “errors to the warm, liquid side,” and I am more likely to forgive small subtractive ones that do not exacerbate the resonances that can pop up throughout the audio chain and pique me. I like things tight and clean.

The system into which I inserted the Power 3 included the already resident Line 3 and the Revel Ultima Studio loudspeakers.

The most immediate improvement of the Power 3 over the 2 was in the extension and solidity of the bass, where the Studios offer ample opportunity for demonstration. Although the 2 was warm and ever so slightly soft at the bottom, the monoblock 3s had steel fists in their velvet gloves, and dealt handily with the demands of Mahler, Widor, and Pink Floyd. No warmth? No, but satisfyingly full and dramatic.

At the other end of the spectrum, in John Culshaw’s pellucid and powerful production of Strauss’s Salome with Nilsson, Solti, and the Vienna Philharmonic (London OSA 1218), not only were Salome’s veils dropped; so, too, was any ambiguity of detail in the upper strings and percussion. The tonal quality of the midrange through the Power 2 and Power 3 may be quite similar but the Line 3s’ clarity and image depth were distinct advances on the Line 2’s. In other words, the combination of Power 3 and Line 3 was even more neutral than that of the Power 2 and Line 2: the former emulated the grinning Cheshire Cat even more exactly as they continued to disappear.

I do acknowledge Brian’s observations on the Power 3: There was some dryness throughout the midrange with the OLS Kharma Ceramique 2 speakers and compared to the McCormack Rev-A DNA-1. With the Revel Ultima Studios (and helped by some recently added acoustic room treatment), there seemed to be nothing missing. The sound was neither rich nor dry, but balanced. I did not feel that the Power 3/Line 3 combo sapped the life from the music, but rather that it offered the music stripped of added embellishment, Soundstage depth and width were beyond cavil, as was instrument localization, but these parameters are more greatly influenced by the speaker/room setup than by the electronics.

Dynamics: I knew I’d have to deal with this. Like most of us, I have two listening modes, and what I hear is often determined by which mode I’m in. With my audiophile (and reviewer) hat on, I listen for the sounds in the music. With my music-lover hat on, I listen to the sounds of the music. in audiophile mode, I heard everything that Brian, almost apologetically, describes as limitations in the Power 3’s presentation of micro- and macrodynamics and how this affects other issues. Yet I have to force myself to listen for them, and would perhaps not have noted them without his suggestion.

But even when I do, I am impressed by how often the Line 3/Power 3 combination simply ravishes me. From the revelation of Dietrich Fischer-Dieskau’s subtly modulated vocal inflections (Cerha’s Baal Gesdnge, Berlin Classics BC 20722) and the interplay of intimate voices in a Jandcek string quartet (Bayer 10051) to the inexorable impact of Mahler’s Symphony 6 (Bernstein, DG 427 9672), the Line 3/Power 3 kept blowing my audiophile hat right offl My impression – directly opposed to Brian’s -was of a very extended dynamic range. I thought the sound quite accurate in terms of dynamics, neither compressing nor emphasizing gradations, and that some contrasts were, appropriately, just not as big as others.

In matters of the audiophile heart, everything’s subjective. If Brian were to visit, he’d probably think that my system sounds damn good; I’m sure I’d have the same response to his. More than likely, we’d both be much happier in our own homes with our own music. It’s not necessarily bad or surprising news that no single component can please everyone. The good news is that, for me, Sonic Frontiers’ Power 3 and Line 3 were completely satisfying. They just got out of the way and let me at my music. In fact, I have bought both of SF’s top-of-the-fine offerings for my reference system.
-Kahnan Rubinson