Audio Files: Why Are Ultra-Low-Power Amps All the Rage Among Audiophiles?

"Flea-watt" amps are being embraced by serious music fans

Triode Labs’ $3,500 2A3S-III
Triode Labs’ $3,500 2A3S-III

Music’s always going to have occasional throwbacks—who would have expected that in 2019 we’d be seeing a renaissance in tubas and tenor guitars? In the related field of high-end audio, though, the throwback may soon become the norm. Many audiophiles are rejecting modern amplifiers that deliver hundreds of watts of power, instead embracing so-called “flea-watt” amps with power ratings of 10 watts per channel or less. Some of these low-powered amps employ technology that was already considered outdated when Sonny Rollins cut his first album. Such amps used to be novelties, but I’d estimate that about a quarter of the demo rooms at most audio shows now feature flea-watt amps.

Can Less Be More?

Why are so many audiophiles forsaking so much power? It’s because of the general belief that the simpler an audio system is, the more the details and subtleties of a recording will come through. Most flea-watt amps use vacuum tubes instead of transistors, and most of these employ a design called “single-ended triode.” A triode is the simplest type of audio tube, and most of these amps use just a single triode per channel, plus another tube or two to amplify the incoming audio signal. If you want a simpler audio system, you’ll have to get a gramophone.

In order to produce reasonably high volume, these amps must be paired with super-sensitive speakers that can produce high sound levels with just a few watts of power. Paired with conventional speakers, a flea-watt amp will likely play only at about the level of typical conversation. That might be adequate for something like a Baden Powell solo guitar recording, but not for any album by a group with a rhythm section.

Fortunately, speakers that deliver room-filling sound from a single watt are increasingly easy to find. Klipsch has been making such speakers since the 1940s, but we’ve recently seen newer companies such as DeVore Fidelity, Tekton, and Zu Audio focusing their attention on flea-watt-compatible speakers.

It’s pretty easy to figure out how loud a flea-watt amp will play with a given speaker. Start with the speaker’s sensitivity rating, which is given at one watt, and figure that every doubling of power beyond one watt will give you an extra 3 dB. So a speaker rated at 96 dB with one watt will give you 99 dB with a two-watt amp, 102 dB with a four-watt amp, and so on. A system that achieves a level of about 100 dB or more should play loud enough for most listening.

But in audio, as in everything else, there’s no free lunch, and the engineering techniques required to get so much volume from so few watts may compromise other aspects of a speaker’s performance. And even with super-sensitive speakers, these systems often struggle to reproduce highly dynamic, bass-heavy music such as fusion, rock, and hip-hop. So while they might cut it for Billie Holiday fans, they’re a poor choice for Billy Cobham fans.

Bottlehead's $1,029, 3.5-watt Stereomour II
Bottlehead’s $1,029, 3.5-watt Stereomour II

The Flea-Watt Circus

Like other audiophile tube amps, most flea-watt designs are priced well into the four figures. There is one low-cost way to explore the world of low-power amps, though: a three-tube amp measuring just 5.1 inches square. It was originally sold as the Miniwatt N3; although it’s no longer available under that brand, the same design is offered on eBay under various brands and model numbers for about $189 plus $45 or so for shipping. It’s rated at just 3.5 watts per channel, and I expect that’s optimistic, considering the amp’s tiny EL84 tubes. But paired with Klipsch’s $199/pair R-51M bookshelf speakers, the N3 or one of its clones should give you enough sound to fill an office or small bedroom.

A nice step up from an N3 clone is Decware’s $999 SE34I.5 integrated amp. It’s rated at just 2 watts per channel in stereo mode, so to deliver satisfying sound, it’ll need a more sensitive speaker, such as Zu Audio’s $2,600/pair Soul, which is rated at 99 dB sensitivity. Or step up a little higher to Triode Labs’ $3,500 2A3S-III. Like the N3, it’s rated at 3.5 watts per channel, but because each channel uses a large 2A3 triode tube, and the power and output transformers are much larger, it’s a safe bet the 2A3S-III has a lot more sonic muscle. You can save a few bucks by building your flea-watt amp from a kit. Bottlehead offers two: the $1,029, 3.5-watt Stereomour II and the $1,849, 8-watt Kaiju.

Whether or not a flea-watt audio system will bring you sonic bliss, I can’t say. But I can confidently state that when you spin your sides through a tiny, single-ended triode amp, driving an exotic pair of high-sensitivity speakers, you’ll know you’re getting a very different listening experience than the average mass-market audio system delivers.

Brent Butterworth

Brent Butterworth has been a professional audio journalist since 1989, and has evaluated and measured thousands of audio products. He is currently a writer at Wirecutter and editor of the SoundStage Solo headphone site; served as an editor at such magazines as Sound & Vision and Home Theater; and worked as marketing director for Dolby Laboratories. He also plays double bass with several jazz groups in Los Angeles.