Cavali Audio Liquid Lightning Electrostatic Headphone Amplifier (Playback 60)

Headphone amps and amp/DACs
Cavalli Audio Liquid Lightning electrostatic headphone amp
Cavali Audio Liquid Lightning Electrostatic Headphone Amplifier (Playback 60)

Dr. Alex Cavalli builds world-class headphone amplifiers partly as a business, but largely as a labor of love. He doesn’t seek to build a lot of amplifiers, but by his own admission hopes that the ones he does produce will win critical acclaim and, more importantly, will find their way into the hands of owners who will cherish them as classics in their own time. Thus far, Cavalli has gotten part of his wish; last year, Playback reviewed Cavalli’s first production headphone amplifier, the Liquid Fire, and pronounced it a “state of the art” component (words we do not use lightly). Moreover, the Liquid Fire has sold well, so that each of Cavalli’s typically small production batches has sold out thus far. Now, Dr. Cavalli is back with a new and even more ambitious product, the Liquid Lightning solid-state electrostatic headphone amplifier ($4250). Why an amp for electrostatic ‘phones, which are relatively uncommon and quite expensive? The short, two-word answer is this: sonic excellence.

We at Playback think, as do many other high-end headphone experts, that the best headphone presently available is the Stax SR-009 electrostatic “Earspeaker” (Stax’s term, not ours), as reviewed in Playback 54.But great though the SR-009 is, its sonic character almost defies description because, as we noted in our review, “the underlying sonic ‘persona’ of the SR-009 can and does shift in both subtle and profound ways as you connect these headphones to different amplifiers and source components.” We went to say that, “the sound of the Stax will always be an uncannily revealing and nuanced rendition of the signature sound of whatever components you happen to use to drive them.”

During a recent conversation Dr. Cavalli told Playback that his primary motivation in creating the Liquid Lightning was to build the finest solid-state electrostatic amp he knew how to design—one that would be, in a sonic sense, “essentially colorless.” Another goal, though, was to create an amp that would perform optimally without requiring any of the painstaking “tube rolling” activities often associated with tube-powered designs. (Cavalli is actually a great fan of tube-powered amplifiers, but concedes that they probably aren’t for everyone.).  Has Cavalli succeeded in making a headphone amplifier so accurate and faithful to source materials that the only sonic “personality” listeners would hear would be that of the music itself. We think so, but read on for more details.


  • Many world-class electrostatic headphone amps are either tube or hybrid tube/solid-state designs, but the Liquid Lightning is a purely solid-state design that uses innovative circuit technology to extract extraordinary performance from high voltage MOSFET devices. Cavalli says, “MOSFETS are more durable than bi-polar junction transistors and can be run at higher power levels in the same space.”
  • The Liquid Lightning uses high-quality parts throughout, such as a TKD Quad Fader volume control, plus more than a few elements custom made for this amp, including:
    • A custom piezo-type power switch,
    • A custom RCore transformer, and
    • Custom made Stax configuration output jacks, which, unlike many competing Stax-type jacks, are precision made to grip Stax connector plugs very firmly and prevent any possibility of users receiving shocks (Stax electrostats reququire 580V bias) when accidentall pressing their fingers against the jack openings.
  • Output: The Liquid Lightning has 400V power supply rails, meaning it can yield an output swing of 1600V peak-to-peak, which Cavalli notes is “a standardized way of specifying the output voltage excursion of electrostatic amplifiers”.
  • The amp has a gain of 500x in single-ended mode, or 1000x in balanced mode.
  • Provides switch-selectable single-ended and balanced inputs.
  • Provides two output jacks, with bias of 580V for Jack 1 (Stax Pro bias), and the owner’s choice of 580V (Stax), 540V (Sennheiser HE60), or 500V (Sennheiser HE90) for Jack 2.
  • The amp has an input impedance of 45k Ohms per signal, which—notes Cavalli—“means that in balanced mode both plus and minus signals are each terminated into 45k Ohms.”
  • The amp power supply has a standby mode and an overload sensing circuit that “monitors the power (current) being used by the amplifier section.” Cavalli adds that if, “usage exceeds a pre-determined amount (because the amplifier is drawing too much current) the power supply turns the Liquid Lightning completely off.”
  • Power cycling safety features: Cavalli points out that “one additional advantage of the power supply is that if there is a power blip (even a very short one) the amp turns off and will not turn on again when power returns. It requires the user to push the switch again. This prevents rapid power cycling that can sometimes damage amplifiers due to fast transient power interruptions.”


When I set out to write this section of the review, I realized many of my initial attempts to describe the sound of the Liquid Lightning came out sounding like Zen riddles, as in, “What is the sound of one hand clapping?” Nevertheless, let me make an attempt at the task.

What is the sound of the Liquid Lightning? In one sense it is essentially no sound at all, by which I mean to say that the Cavalli is as free from colorations, distortions, and moments of transient excess, ringing, or overshoot as any headphone amp I’ve yet heard. In other words, it reproduces music without injecting much if any sonic personality of its own into the proceedings. In another sense, though, the sound of the Cavalli is very much the sound of the recordings and source components with which it is fed, with nothing added and nothing taken away. In my experience, it seemed that no detail or sonic nuance—no matter how small—could escape detection by the Liquid Lightning; the amp just finds whatever’s there and reproduces it cleanly without fuss, bother, or histrionics.

The Cavalli has positive qualities in abundance: dead neutral frequency response, ultra low levels of background noise, terrific transient speed, stunning resolution of low level details, and powerful and expressive dynamics. But the amp is more than the sum of these qualities, because what it really brings to the party is an effortless and unforced quality of sonic honesty—as if it has sworn to tell the truth and nothing but the truth. As the motto engraved on the wall of the CIA headquarters put things in a passage drawn from the Gospel according to St. John, “ shall know the truth and the truth shall make you free.” Or at least that’s the theory.

When coupled with the Stax SR-009 the Liquid Lightning offers listeners an extraordinarily precise and detailed view of the inner workings of recordings—a view so accurate and revealing that you quickly find yourself becoming a discerning connoisseur of the finer aspects of recording and mixing techniques. With the Stax/Cavalli combo on the case, it becomes child’s play to draw subtle qualitative distinctions between tracks on an album, or even to spot ultra-subtle qualitative variations between passages within an individual track. If, down deep, you’ve always dreamed of hearing all of the music, the Stax/Cavalli combo may well be the state of the art package to make those dreams come true.

There is, as so often is the case with such things, an upside and a downside to the Cavalli’s capabilities. The upside is that more or less everything you could ever want to know about a recording is laid bare before you. The downside is that sometimes great music winds up being captured in highly imperfect recordings where hearing the flaws that are present (and in explicit detail) can leave you feeling less than blessed (or perhaps simply overwhelmed with more information than you can readily process). Either way, the Cavalli just keeps on telling you the truth, no matter what.

Are there drawbacks? Well, one small drawback is that the Cavalli needs about 200 hours of run-in time during which time the amp will, as Cavalli product documentation points out, “continue to improve with regard to bass impact, more open sound, warmth, and ‘sweetness’…” Our listening tests confirmed this. When first heard before adequate playing time has been accumulated, the amp can initially sound a little sterile and mechanical. But give it time; the longer you play it, the better it sounds.

Next, the amp does—for each listening session—need a fair bit of warm up before it is truly ready to sing. Cavalli recommends a minimum of 15-30 minutes of warm up time, but I found an hour or more made it sound even better. When cold, the amp is playable but again sounds a bit thin and edgy before it is fully warmed up.

How does the Cavalli compare against the two other world-class electrostatic headphone amps we’ve recently reviewed? I would say the Cavalli is fully the equal of the Woo WES with upgraded tubes in terms of clarity, definition, and dynamics, but with two important differences. When you listen to the Woo WES, you are always conscious of it delivering a finely resolved, ultra high-definition sound, but you may also wonder whether the Woo could be—in an almost subliminal way—achieving perceived definition by subtly overemphasizing the leading edges of transient sounds. By comparison, the Cavalli is no less finely resolved or well defined, yet it does not give an underlying sense of overemphasis; instead, details unfold in a natural way that is almost self-effacing in its honesty and directness. Second, as my colleague Tom Martin noted in his Woo WES review, the WES can at times sound “somewhat stressed or shouty on vocals,” which, Tom felt, “suggests a frequency response elevation in the midrange.” In contrast the Cavalli has no such hints of midrange elevation so that it generally sounds smooth (assuming the recording itself is smooth) yet very, very focused.

The other great electrostatic amp we’ve recently evaluated is HeadAmp’s terrific Blue Hawaii SE, which in a sense stands as the yin to the Woo WES’ yang—an amp that, while offering plenty of resolution and detail, focuses strongly on capturing the warmth, life, and overall integrity of the music. As reviewer Tom Martin put it, “the Woo tends to deconstruct music into its component parts, while the Blue Hawaii reveals the parts but deftly reconstructs them to present a musical whole that make sense.” Where does the Liquid Lightning fit within this picture? The simple answer is that it finds a middle path somewhere between these two competitors. It is every bit as revealing as the Woo, yet rarely draws attention to itself in ways the Woo sometimes does, perhaps because it avoids exaggerating midrange frequencies and transient details. The Cavalli shows you what’s there, but not more than that. At the same time, the Cavalli also expresses much of the warmth and life in recordings (assuming the record in fact possesses those qualities), not by enhancing “warmth” or “life” in any way, but by simply revealing what’s already there.

The important thing to remember is that all three of these amps truly deserve recognition as world-class products; the differences between them, though readily observable, are nevertheless fairly subtle. Which you prefer could be largely a matter of personal taste, although I think there is much to be said for the “middle path” approach that the Cavalli amp brings to the party.

One final note on living with the Cavalli/SR-009 combo: You should prepare yourself for the fact that the Cavalli/Stax pair will very likely show you things you don’t already know about your favorite source components or recordings. Be prepared, therefore, for surprises and new discoveries. As heard through the Cavalli, differences between ancillary components become easy to hear and assess, while recordings open up in unexpected new ways—sometimes revealing previously hidden sonic riches, but occasionally exposing sonic “clunkers.” My point is that the Cavalli amp leaves nothing on the table, sonically speaking; it will give you everything your recordings have to offer, every time you fire it up—a prospect that is at once very exciting, but at times just a bit intimidating. Can you handle the truth?


As I mentioned above, the Cavalli invites you to become a connoisseur of recording and mixing techniques, and it also can show you why in some cases simpler two-microphone recording techniques can yield better (or at least more coherent-sounding) results than more elaborate multi-mic processes. A great example would be the gorgeous Jim Merod/Steve McCormack recording of the Joe Wilder – Marshall Royal Quintet on Mostly Ellington [BluePort/NuForce CD & 96/24 DVD]. Listen to “Mood Indigo” from that track and note how grippingly realistic Royal’s alto sax sounds. You’ll not only hear the rich, pure, sophisticated tonality of the horn itself, but also the almost subliminal fingering and mouthpiece/reed noises and occasional sound of breaths being draw in as Royal plays. The presentation is incredibly clear, nuanced, and profoundly revealing. Later, when Wilder joins in with his trumpet, the same level of realism prevails. But what the Cavalli will go on to show is that the entire track gives consistently great treatment to each of the instruments in the ensemble—there are no quality shifts or drastic changes in listening perspective as the focus moves from one soloist to the next. This is the sort of listener’s judgment call that the Liquid Lightning enables you to make with complete certainty; there is nothing ambiguous or equivocal about its sonic presentation.

The Liquid Lightning also does justice to well-recorded pop/folk music, as you can plainly hear if you listen to “Closer” from Steve Strauss’ Just Like Love [Stockfisch, Multichannel SACD]. This is a terrific studio recording that uses multi-mic recording techniques, which was recorded and produced by the very gifted Günther Pauler of Pauler Acoustics. Pauler tends, in my experience, to give his pop/folks recordings a slightly larger-than-life quality, a fact that the Cavalli of course makes obvious, but in a way that tends to present each instrument and voice in the most favorable possible light. A good example would be Strauss’ voice, which while not “beautiful” in the traditional sense, is nevertheless rich, touched with a just-right amount of grit and texture, and full of expression. As Strauss sings, the Cavalli shows you Pauler takes certain small, tastefully applied production steps to maximize the singer’s strengths while minimizing his weaknesses (in particular, a tendency for the voice to sound overtaxed on bigger vocal swells). Thus, you’ll hear Pauler adding subtle bits of reverb to add sweetness and depth, or managing relative gain levels to help keep Strauss’ voice in its comfort zone. Happily, each of the instruments in play gets the same careful treatment, so that you’ll easily hear the light, delicate, dancing quality of Strauss’ acoustic guitar, the haunting arc of Beo Brockhausen’s soprano sax, and the deeply evocative and richly textured growl of Hans-Jörg Maucksch’s fretless electric bass. As each element takes its turn in the spotlight, you may find that the listening perspective shifts just a bit (something that almost inevitably happens in multi-mic recordings and that the Cavalli amp plainly exposes), but in each case the perspective chosen seems nearly ideal for the instrument and/or musical passage at hand. But above all, the Cavalli leaves you with not only with the enjoyment of having heard a beautiful track beautifully reproduced, but also with the sense of having gleaned insights into the way the record was made. If you enjoy insights like these, then you have grasped a big part of the Liquid Lightning’s appeal.

The inherently quiet backgrounds afforded by the Liquid Lightning are part of the secret to its resolution, as you’ll quickly discover if you play a recording whose output levels have been mastered toward the lower end of the spectrum. Some good examples would be most any track on Professor Johnson’s 30th Anniversary Sampler disc [Reference Recordings, HDCD], which is rightly regarded as something of an audiophile classic. On first playing, it becomes obvious that signal levels on the disc are much, much lower than for typical pop recordings, so that you may feel the need to dial up amplifier gain levels considerably higher than you would with run-of-the-mill records. But with some amps this can be a tricky proposition, because as gain levels come up so, too, do noise floor levels, which inevitably robs listeners of some measure of low-level resolution. Happily, this doesn’t happen with the Liquid Lightning; even with gain levels turned up quite high the noise floor remains very low, so that you can have the gain you need without paying a sonic penalty. The reward, as you’ll discover if you listen, for example, to the excerpt from the angular, modernistic, and at times quite percussive Skrowaczewski Concerto Nicolò from the 30th Anniversary Sampler disc is a Tour de’ force in tonal colors, transient attack, dynamic expression, and inner detail. It’s a breathtaking recording made even more enjoyable and intelligible by the Cavalli amp’s low noise, an amp that proves the truth of the old adage that, “less noise = more usable sound.”


Consider this electrostatic headphone amp if:

  • If you want what is arguably the most accurate, neutral, agile, and transparent-sounding electrostatic headphone amp there is—one that perfectly complements the capabilities of the Stax SR-009 headphone.
  • You delight in hearing exactly what’s in your favorite recordings, right down to the most minute of details. With the Cavalli, you have the eerie sense of looking, figuratively speaking, over the record producer’s shoulders to learn how recordings are put together.
  • You find it thrilling to hear subtle textural variations, transient sounds, dynamic modulation, and inner details that other amps either miss or exaggerate. The Cavalli simply tells it like it is.

Look elsewhere if:

  • “You can’t handle the truth,” as Jack Nicholson famously snarled in the film A Few Good Men. Some folks love getting all the information; others find it a burden (or even a source of irritation).
  • You want a more relaxed or perhaps more romantic sonic presentation than the Liquid Lightning provides. The Cavalli’s “just-the-facts-Ma’am” honesty isn’t for everyone.

Ratings (relative to other cost-no-object electrostatic amps):

  • Tonal Balance: 10
  • Clarity: 10
  • Dynamics: 9.5
  • Input/Output Flexibility: 9.5
  • Value: 10 (while undeniably expensive, the Liquid Lightning is actually the least costly of all the world-class headphone amps we’ve tried).


The Cavalli Liquid Lightning electrostatic headphone amplifier is arguably the most honest and revealing amplifier that money can buy for purposes of powering electrostatic headphones in general and in particular for driving the state-of-art Stax SR-009 headphones.


Cavalli Audio Liquid Lightning
Inputs: one fully balanced stereo analog input (via XLR jacks); one single-ended stereo analog input (via RCA jacks).
Outputs: two five-pin Stax compatible output jacks
Output Voltage Swing: 1600 V p-p
Bias voltage(s):

  • Output Jack 1—Stax Pro bias: 580 V
  • Output Jack 2—Owner’s choice of: 580V (Stax Pro bias), 540V (Sennheiser HE60 bias), or 500 V (Sennheiser HE90 bias)

Dimensions (H x W x D):3.9” x17” x 15.12”
Weight: 23 lbs.
Warranty: 1 year, parts and labor.
Price: $4250

Manufacturer Information
Cavalli Audio
(512) 413-8765

blog comments powered by Disqus

Featured Articles