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Shout It Out Loud: Digital Amps

When Miles Davis went electric in the late 1960s he caused quite a stir, to say the least, alienating old fans along the way because they were unable to share his vision of the future. His sin? He chose to place a proven musical-instrument technology into a context where a certain purity, assumed of only acoustic instruments, was the norm, and his foray into this new territory for jazz players made sparks fly-literally and figuratively.

We are at a similar juncture in audio, though the coming revolution is happening unbeknownst to most of us. Actually, the revolution started some time ago with the advent of CDs. The current skirmish is just one of the final fronts in the invasion of binary devices. Get ready: we are entering the age of digital amplification, to the abject horror of many audio purists.

Change scares some people, and, after the inexcusably bad sound of many early CD players and discs, it is no wonder that the idea of sacrificing yet another component in the audio chain to the choppy, screechy ills of digititis has raised more than a few hairs on the backs of a few necks.

But the fact is that the current generation of so-called digital amps does what amplifiers are supposed to do: make good music sound like good music.

“All designers of digital amplifiers must overcome a double deficit in the minds of the audiophile,” says Allen Perkins, U.S. importer of the new Audio Physic Strada digital amp. “They must overcome the stigma of designing a solid-state amplifier and the stigma of designing a digital amplifier.” Perkins makes note in this statement of the fact that solid state or transistor-powered designs have also taken a bad rap in the high-end audio world because of their often harsh, nonmusical and fatiguing sound, leading many to the greatly expanded pool of euphonic tube amps.

This is where it gets interesting: many new digital amps are being hailed by critics as exhibiting the best attributes of solid state-solid bass handling and reliability-and the best of tubes-lifelike midrange and more natural sound overall-creating what is being touted as the future of amplification.

Paul McGowan of PS Audio, and a long-time legend in the high end, has just launched his company’s first digital amp, the HCA-2. He sums up the digital solution this way: “If you can make an amp that sounds like a tube amp in terms of musicality but that doesn’t die over a period of time, as do tubes, then you have something special.”

A similar statement comes from John Stronczer of Bel Canto Design, a company renowned for its simple, powerful tube amplifiers since the mid-’80s. “Our new amp evolved from our tube designs, which were seductively capable of communicating a musical message, to deliver something emotional to the listener. But good, reliable tubes are getting harder to find,” Stronczer says, “and we realized we needed to find some kind of solid-state technology that would allow us a path to the future.”

But fits and starts are common in the evolution of any new idea. “A few digital amps in the recent past have been lackluster,” McGowan says. “Only now has the technology gotten good enough to be explored by designers who actually design by listening. These first-generation digitals were built by engineers who didn’t listen but designed on their scopes as was the case with early CDs.” No wonder audio critics had precious little praise for these pioneering digital amps.

So why does the current generation of digital amplifiers perform so well?

“They share tubes’ simplicity,” insists Stronczer. “In a traditional solid-state amp, by the time you get to a reasonable output level, say 100 watts, you have a large number of parallel output devices [transistors] that might be fighting each other in their job of driving the speaker when they should be operating in unison. But utilizing digital technology allows us to create a more efficient design and as the design gets more efficient, it gets simpler and better by eliminating wasted energy. The better focused the device-one that uses the minimum amount of energy to achieve its goal-the better it will be. Part of efficiency is getting rid of unnecessary components in the circuit. We can deliver as much as 2,000 watts of power with only four output devices where a traditional solid-state amp would need 40, and they would all need to sing together, which we all know never happens.”

Efficiency and simplicity are terms that pop up constantly when talking to any of these digital-amp gurus. Digital designs-and there are many competing ideas out there-tend to pare the circuits down to an essential few parts, some aspects of which are controlled by the ultrafast switching on and off of new digital chips or other components that are obviously harvested from the increasingly sophisticated computer industry. “We are at the edge of technology right now,” McGowan says. “As these devices get faster our amps will probably sound even better.”

Because of the way they operate, switching on and off in a manner that is notoriously inefficient, most solid-state amps waste a lot of power, converting only about 50 percent of the juice from your wall plug into watts for your speakers. Digital amps, on the other hand, are as much as 90 percent efficient, meaning if you suck 100 watts from the wall, you get 90 at the speakers. One of the byproducts of the inefficient operation of traditional solid-state devices is heat, which must be dissipated, usually with large metal heat sinks that get very hot and add greatly to the weight and cost of producing an amp. Says McGowan of his new design, “We could not produce this amp at this price [$1,695] if it were a traditional solid-state amp because of the cost of the metalwork needed to get rid of the heat.”

So with fewer parts and no need for heavy, bulky heat sinks, another advantage to digital amps is their shrinking size. This ability to put a relatively powerful amplifier in a very small space offers a number of possibilities coming down the pike-no wait, the possibilities have already arrived, realized by more than a handful of forward-thinking designers looking for just such a space-saving solution, including computer-maker Apple (the Mac Cube was an early adopter of digital amps) and many subwoofer manufacturers, which use them to power subs with hundreds of watts without creating heat. Car-audio guys are catching on fast for obvious reasons, as are Sony, Kenwood, Samsung, Sharp and countless others. You may very well own a digital amp right now and not even know.

Another point McGowan, Stronczer and Perkins seem to agree on is that digital amps are in everyone’s tomorrow. To paraphrase all three: “Because it can come in a cheaper, smaller package and still sound great, this will become the dominant form of amplification in the very near future. It comes down to cost, power, heat, size and weight.”

So do they really sound good?

“When we hooked up a prototype of our eVo amp,” Stronczer says, “my assistant and I looked at each other and both said, ‘Does this sound as good to you as it does to me?’ There was something inherently right there. It was communicating something we didn’t expect from a solid-state amp, which are normally unable to transmit a vital part of the essence of the music, something tube amps usually get right. From the beginning, this new concept really worked for us.”

McGowan echoes that sentiment in regard to his HCA-2: “The sonic characteristics are stupendous, the micro and the macro dynamics are untouchable and the midrange is spectacular. We don’t know how to produce a conventional amp that can duplicate the superior sonics of this amplifier.”

Likewise, Perkins describes the Audio Physic Strada ($18,000 for a pair of mono amps built in Germany) as possessing “a more effortless sound quality that is smooth and relaxed, yet has an iron grip on the speakers to produce fast, accurate bass with 250 watts of absolutely clean power.”

There is no one digital solution; all the amplifiers mentioned here utilize different methods of incorporating some sort of digital technology into the “topology” of the design, and it is beyond the scope of this column to explain each. (For more reading on these difficult-to-explain technologies, check out and

Is one method right and the other wrong? Different strokes for different folks. Like any other piece of equipment, if it sounds good to you and it fits your budget, it’s worth considering.

PS Audio has just introduced its HCA-2 and the response has been very positive so far. To my ears, it does indeed possess a very tubelike sound, which is my personal preference. Pumping out 150 watts, it is capable of window-rattling bass that, though deep and loud, never gets out of control and is never less than focused and crystal clear. And the HCA-2’s ability to position instruments precisely across the virtual stage is amazing. I was not aware of any of the harshness so often noted with traditional solid-state amps, which allowed me to spend many an evening on the couch soaking up Kevin Mahogany, Kip Hanrahan and the new SACD version of Mingus Ah Um, which has never sounded better, thanks in large part to the HCA-2. And just like McGowan says, the thing produces no heat-the box stays about at room temp.

The solid-state hurdle has been overcome, and despite my antidigital bias, this PS Audio amp reveals nuances in my CDs that I have never heard before. Its sound is pleasing, involving and hits those emotional points we keep hearing about yet rarely experience.

McGowan says his company is preparing a multichannel amp for home-theater applications using SDAT technology-the term PS Audio uses for its digital solution. The company will also introduce an integrated model that will incorporate PS Audio’s new preamplifier, the PS 8.0, and the HCA-2 amp in one box for under $2,500. Quite a steal.

Bel Canto’s recent digital entries are also deals. I remember hearing a Bel Canto tube amp at a friend’s house a few years ago and was quite impressed with its dynamic, easy-to-listen-to sound. Well, the company’s new line of eVo products and its self-described “evolutionary” digital amps have all that and more without ever having to replace a single tube.

The eVo2i is Bel Canto’s integrated amp, combining the basic 120-watt eVo 200.2 amp and the eVo PRe1 preamp into one box for only $3,200, shaving $1,600 off the price of the two components bought separately. I can’t even begin to tell you all the features this thing offers via its chip-driven, rock-solid, remote: multistage muting, custom-labeled input selection, stepped balance, standby mode and lots more. Well, OK, I did begin to tell after all, but there are lots more. I could love this thing just for the remote.

And the sound of the eVo2i? Let’s just say, “Hot damn!”

After living with some great tube gear for the last decade or more, I may finally be able to admit that not all solid-state equipment sucks. Like the PS Audio, this beauty (and they are both beauties in their external design as well as internal) exhibits the startling realism normally associated only with very good tube amps. Bursts of cymbal crashes, salvos of tight, properly chunky guitar chords and a piercingly high sax lick can all sound lifelike.

I can’t get enough of Keith Jarrett’s Standards Trio and play the many superb recordings of this always-intriguing group incessantly, especially when evaluating new equipment. The eVo2i does something that I have never heard before, and that is to delineate-with pinpoint accuracy-the band’s on-stage presence exactly as I have been lucky enough to experience it on several occasions in person: Jarrett on the left, Gary Peacock and bass tucked neatly just left of center and Jack DeJohnette and his drums to the right. What confounds me most is how well the eVo sculpts the drums exactly as they are laid out, even hinting at the vertical positioning of the bass drum, but clearly painting a hi-hat far right, the snare a bit to the left, followed by a tom or two and that amazingly dry ride cymbal just before Peacock’s rig takes over. I almost feel like I could saunter over and sit down behind these 3D Sonors.

This is the way I imagine a stereo should sound, and I never tire of listening to music-getting all that a performer has to offer-on this system. I have been pulling out old favorites for reexamination and continue to find delights in all of them. Listening to a circa-1970 recording of Brazilian samba diva Beth Carvalho reveals a breathiness in her voice and a palpability I had never noticed before, not even on the vinyl version of the same recording. I can’t yank material off the shelves fast enough to keep up with my passion to hear more and more of what this box can do.

The eVo line also features a four-channel and a six-channel version of the amp for surround systems and home theater. To goose their systems, some savvy listeners are buying the four-channel model and setting it up as a stereo unit, doubling the power and increasing the quality of the sound even more. In addition, Stronczer may offer a phono preamp in the integrated version and hints at an all-in-one unit that would include a CD player, the preamp and the amp-plug and play. Just hook it to your speakers and roll.

Another advantage of digital amps is that, by and large, they are capable of driving about any speaker load out there, so system matching will be much easier from now on.

I have to admit, before starting work on this column, the thought of adding another digital link to my audio chain was not unlike running some very long, sculpted nails down a very dusty chalkboard. But after hearing the PS Audio and Bel Canto amps up close and personal, I might just have to reassess the contents of my equipment.

Originally Published