Three Top-Tier Headphone Amplifiers for Hardcore High-Enders

Headphone amps and amp/DACs
Apex Hi-Fi Peak Headphone Amp and Volcano Power Supply,
Cavalli Audio Liquid Fire Headphone Amp,
Woo Audio WA 22 Headphone Amplifier
Three Top-Tier Headphone Amplifiers for Hardcore High-Enders

If you’ve spent much time reading our sister magazine The Absolute Sound, then it will come as no surprise to learn that true top-tier stereo systems (complete with killer speakers, amplifiers, source components, cables, etc.) can easily run deep into six figures (yowza!). Make no mistake; when done right, such high-end systems can sound fabulous. Still, relatively few of us can afford to make that sort of investment in our sound systems. What if you want to go to the sonic mountaintop, so to speak, but don’t have a small fortune to spend?

This is where many Playback readers would argue that top-tier headphone-based systems could be a very enticing alternative to conventional ultra high-end hi-fi systems. Although top-tier headphone rigs are by no means inexpensive, they are vastly more affordably priced than their traditional high-end audio counterparts.

One of the prerequisites for a first class headphone system would be a top echelon headphone amplifier, and this article will introduce (or perhaps reintroduce) readers to three of the finest top-tier headphone amplifier options Playback has thus far encountered.

Apex Peak Headphone Amplifier & Volcano Power Supply ($2095 - $2230, as tested)

To read the full review:

What it is: The Apex Peak/Volcano is a two-chassis, hybrid tube/solid-state-powered headphone amplifier/linestage preamplifier. The amp provides three line-level single-ended stereo analog inputs, one variable-level single-ended stereo analog output, and a single-ended ¼-inch phone jack headphone output. The U.S.-made amplifier uses a top-mounted 6SN7 vacuum tube, which means that tube-rollers can experiment with various types of tubes to optimize sound quality. For our tests, we used an Apex-recommended 6SN7 upgrade to a Shuguang Treasure CV181-Z grade A tube, which sounded simply terrific.

Why you might choose it: Let’s acknowledge up front that the Peak/Volcano is versatile in at least two ways. First, it can serve both as a very high-quality headphone amplifier, but also as a fine albeit minimalist stereo preamplifier for a full-sized hi-fi system. Thus, depending on your personal application scenario, you may be able to get “double duty” out of the Peak/Volcano pair.

Second, let’s note that the Peak/Volcano isn’t an “all or nothing” proposition. Instead, you can buy this product in an incremental way, starting with the Peak alone (which comes with a pretty basic power supply for $1395), then add the much beefier Volcano power supply later on ($700), and finally add the Shuguang tube upgrade as a finishing touch ($135).

But the real reason to buy a Peak/Volcano involves sound quality, pure and simple. Specifically, you buy this product because it offers simply mind-blowing levels of resolving power. In all seriousness, when used with top-tier headphones, the Peak/Volcano can create the eerie illusion that your brain has somehow been “hardwired” directly into the recording/mixing console (as if you are hearing exactly what the producer heard when the recording was made). That, my friends, is a pretty darned exciting—not to mention illuminating—listening experience. Instrumental separation is amazingly good, too, so that you can easily follow even the subtlest of musical threads within a mix. Finally, note that the voicing of the Peak/Volcano helps compensate for some of the sonic deficiencies heard in even today’s best headphones.

Why you might look further: Great though the Peak/Volcano is, it’s not perfect in that its ultra high levels of resolution do, in a sense, come at a price. Specifically, there are some circumstances where you might hear very faint hints of a “whitish” or edgy sound on hard transients, or equally faint traces of strain on extremely dynamic passages. Finally, the amp sounds very tightly controlled, but also just a little lightly balanced in the bass region, which means the Peak/Volcano tends to put a bit of a spotlight on the midrange of the music. If you favor that subtle touch of midrange emphasize, look at the Apex (or perhaps the Woo, below), but if you feel a slightly more reserved/balanced midrange presentation would be best, then consider the Cavalli, as below.

Cavalli Audio Liquid Fire Headphone Amplifier ($3250)

To read the full review:

What it is: A US-made, hand-built, ultra high-quality hybrid tube/solid-state headphone amplifier of minimalist architecture. The amp provides a single, line-level single-ended stereo analog audio input with two single-ended ¼-inch phone jack-type headphone outputs. One of the amps two output jacks features an output impedance of ¼ ohm, while the other can be configured to provide the user’s choice of ¼, 50, or 100 ohm output impedance (a detail touch we find near-brilliant). The amp uses four JJ Tesla 6922 tubes for voltage amplification, with a combination of conventional and MOSFET transistor for all other amplification. Very high quality parts are used throughout.

Why you might choose it: To state things simply, this is the first and thus far the only product that Playback has ever described with this coveted four-word phrase: state of the art. What makes it a state of the art component? For starters, the Liquid Fire offers neutral voicing, which means that the amplifier imparts no discernible sound of its own (what you hear is what the recording presents for you to hear—no more, and no less). Next, the Cavalli is an absolute ace at retrieving low-level signals, meaning it lets you hear way down deep into the innermost recesses of well-made recordings. Third, the Liquid Fire offers astonishingly realistic instrumental separation, never smearing instruments together no matter how complex a recording might be. Finally, and this is the tricky part, the Cavalli does all of the above without losing the inherent smoothness, richness, and warmth of well-recorded music. Last but certainly not least, the Liquid Fire can drive just about any headphone on the planet, no matter how power hungry it might be or how “difficult” a load it might present.

Why you might look further: We can think of only two reasons to look further. The first is that the Cavalli might be too pricey for your budget (we feel the Liquid Fire is worth the money, but there’s no denying that hand-made products of this caliber come at a price). Second, you may find that—for your specific application—the Cavalli’s sonic neutrality and honesty (which are for the most parts “plusses” in our book) may not give ideal results with your chosen headphones. In particular, if you favor an amp that, in subtle ways, makes the midrange of the music sound more vivid or intense, you might prefer either the Apex or the Woo. But no matter what, do give the Cavalli a listen if top-tier sound is your objective.

Woo Audio WA22 Headphone Amplifier ($1900 - $2450, as tested)

To read the full review:

What it is: The WA22 is the next-to-the-top model in Woo Audio’s extensive family of high-end headphone amplifiers. Like all Woo amplifiers, the WA22 is a tube-powered design, and in this case is a fully balanced, transformer-coupled design.

Alone among the three amplifiers referenced here, the WA22 can support headphones wired either for single-ended (that is, traditional ¼-inch phone jack-type) outputs, or wired for use with balanced outputs (as supported by either single four-pin or dual three-pin XLR connectors). What’s the significance of supporting balanced outputs? Many high-end headphone aficionados feel that top-tier headphones simply sound better when wired for balanced mode operation (although there is not universal agreement on this point). Happily, the WA22 lets you pick and choose your preferred mode of operation at will. Note, too, that the WA22 provides both single-ended (RCA jack) and balanced (XLR connector) analog inputs.

Like the Apex amp, above, Woo’s WA22 can be ordered in standard form ($1900) or with any of the following tube upgrades: hand-picked, matched pair of Sylvania 7236 NOS 1963 power tubes ($120), hand-picked matched pair of Shuguang Treasure CV181-Z/6SN7GT driver tubes ($280), and a Sophia Princess Mesh Plate 274B rectifier tube ($150). So, as with the Apex, you can start out with a standard Woo WA22 and upgrade its tubes over time, or you can order it up fully “hot-rodded” from the factory. It’s your call.

Why you might choose it: Aesthetics and self-evident build quality; when you’re spending north of $2k on a headphone amp, you want it to look cool, which the WA22 most certainly does. There’s a certain fineness of execution about this (and frankly, all) Woo product that provides both visual and tactual cues that remind you that you are getting your money’s worth and then some. In the case of the Woo, the amp’s fine look and feel mirrors its underlying sonic qualities.

Playback reviewer Tom Martin said of the WA22,

“A description of the sound of the Woo sounds like an audiophile rave checklist. It is transparent, particularly in that you don’t notice any treble veiling or grit as you do with some lesser headphone amps. Bass is solid, well defined and can be very deep with the right headphones. Tonal balance is very, very good, with no sense of treble roll-off or brightness.

This is one of those difficult-to-review products because it is hard to find deficiencies.”

Finally, let’s remember that the Woo gives you complete freedom to explore and experiment with the joys of using headphones wired for balanced mode operation. It also provides both single-ended and balanced analog inputs—a relative rarity in headphone amplifiers.

Why you might look further: One of the WA22's greatest sonic blessings might, under some circumstances, be a drawback. Specifically, the midrange of the Woo tends to sound, says Tom Martin, "slightly more present and vivid... than with other headphone amps I had on hand (at the time of the review)." Tom adds that, "the effect that I'm talking about doesn't sound like a frequency response bump, but rather like an increase in midrange contrast." If you like the idea of heightened midrange presence and vividness, consider the Woo (or perhaps the Apex), but if you favor a more strictly "textbook neutral" presentation, consider the Cavalli. 

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