Solid State Power Amp Reviews

When Paul Bolin reviewed Halcro's dm58 amplifier2 in the October 2002 Stereophile, he pronounced it that rarest of the rare: a truly revolutionary audio product. Its technology was unusual; Philip O'Hanlon of importer On a Higher Note speculated that, "were most electrical engineers to examine a schematic ... few would even recognize it as being an audio amplifier." John Atkinson found it to have "astonishing measured performance for an amplifier," and often felt that he was measuring the limits of his test equipment instead of the amplifier. Sonically, the $29,990/pair dm58 was far beyond anything PB had ever heard—an embodiment of futurist Arthur C. Clarke's maxim that "any sufficiently advanced technology will be indistinguishable from magic."

Wow—where do you go from there? Halcro followed the dm58 with the dm10 preamplifier and dm38 stereo amplifier, both praised in these pages: the dm10 by PB in April 2004, the dm38 by JA in October 2004. Other products—a line stage, more powerful stereo amplifiers, multichannel gear, an SACD player—have been introduced or promised. Rumor has it that some of these may be heading my way, so JA suggested that I spend some time with the dm58, both as a warmup and to see how PB's words held up to three years of 20-20 hindsight.

The last four years of the evolution of high-end electronics confirm that the dm58s were indeed revolutionary. Their performance—what PB described as their "pristine and wholly continuous clarity," "unlimited dynamics," "impossibly low noise floor," and the "remarkable ... directness and completeness of their musical communication"—was paradigm-shifting not only for PB, but for other designers as well. More than one of Halcro's competitors has confided to me that the dm58's effortless, clear, completely neutral sound established a new performance standard that ultra-high-end customers now expected.

My six months with the dm58s have confirmed that PB's assessment was right on the money. Everything he said remains true: their uncanny silence, effortless dynamics, and, perhaps most of all, their incredible clarity, transparency, and neutrality—all were there in spades. Like Paul, I was left scratching my head and searching for some sort of sonic signature, or any evidence that the dm58s were in the system at all. I often think of gear as either "projecting" the images and soundstage, or "dropping away" to leave the performance behind. The dm58s were definitely in the latter camp, but they didn't just drop away—they vanished.

As had PB, I found that I could easily hear other colorations and changes in my system in a way that simply wasn't possible before. It was fascinating to compare Analogue Productions' SACD and LP versions of Cannonball Adderley's Know What I Mean (Riverside/Analogue Productions RLP 9433). On the analog side, I scrubbed the record, leveled up the VPI TNT HR-X turntable, tweaked the stylus pressure and VTA, and worked through three different sets of cables. Each change made a clear difference that was often a dramatic one as well. There were fewer variables to tweak with the SACD, but changes of cables and various models of Finite Elemente feet produced similarly dramatic changes. My review of the TNT HR-X is in the works, so I'll not tip my hand, but this exercise—and the dm58s—allowed me to isolate and characterize my analog rig's sonic signature to a degree I'd never been able to before.

I suspect that another reason JA sent the dm58s my way was for me to hear them beside the VTL S-400, a tube amplifier that I pronounced revolutionary when I reviewed it for the December 2005 Stereophile, and described in much the same way as Paul had the dm58s. In fact, the two sound—or don't sound—more alike than they do different, and more like each other than either sounds like anything else I've heard. There are differences, but their dynamics, neutrality, and clarity, and the way they "vanish" to leave behind only the musicians and the soundstage, are really quite similar. It's astonishing that such different technological paths can converge. It supports the truism that, at the limit of quality and technology, all amplifiers will sound alike, and what they will sound like is nothing at all. Short of that, all we're doing is comparing different sets of distortions.

The VTL is slightly more dynamic at the softer end of the spectrum, and its soundstage is a bit more forward. The Halcro had a slightly deeper, wider soundstage and smaller images, which accentuated the spaces between individual musicians. I'd describe both as tonally neutral, or maybe just a shade cool, but the Halcro always seemed a bit more neutral. This might have been due to the VTL's higher output impedance and greater interaction with the loudspeakers. I did find the differences between the amps to be subjectively greater with the Wilson Audio Sophias than with the Thiel CS6s, the latter having a flatter impedance curve across the audioband. Another slight difference was that there always seemed to be a bit more "there" there with the VTL S-400. Could it be that its greater harmonic distortion was adding a touch of body and complexity?

Both amplifiers are benchmark products and way beyond excellent, superb, incredible, or any other superlative I can think of. When pushed by Wilson Audio's John Giolas during the setup of my Sophias, I thought hard and chose the VTL, which I found to be oh-so-slightly more involving. János Starker's cello on Bach's Suite 1 in G (SACD, Mercury Living Presence 1 470 644-2) sounded richer and woodier through the S-400, and the textures of both the instrument and the surrounding space felt slightly more real. But I'm really splitting hairs here. Other factors—price, cosmetics, the logistics of two chassis vs one, tubes vs solid-state, heat, power consumption—are likely bigger considerations than sonic performance. You can't go wrong with either of these stellar amplifiers.

Paul Bolin had it right: The Halcro dm58 is a truly revolutionary, paradigm-shifting audio component. Light-years beyond anything else in 2002, it sent other designers back to their drawing boards. That now, three or four years later, we're beginning to see other products that can challenge the Halcro, doesn't in the least diminish designer Bruce Candy's achievement or the dm58's performance. The Halcro dm58 is an incredible amplifier; unless you've heard it or one of its siblings, you haven't heard what high-end audio is capable of.—Brian Damkroger