October 2018

World Premiere Review!
Monoprice Monolith Liquid Spark Headphone Amplifier Review
For His Next Trick: Fitting a heavenly-sounding amp into the palm of your hand!
Review By Dave Hanson

  I first met Dr. Alex Cavalli at Rocky Mountain Audiofest in 2015. It was during the press-only event in the hour before the opening of the show.  I had just visited the HiFiMAN booth, and had been listening to the freshly debuting Edition X and comparing it with the still-pretty-new HE1000. As I finished, my friend grabbed me and said, "Hey, I want you to hear something."

He walked me over to a tall, thin man donning a white beard, glasses, and a cowboy hat and said, " I want you to meet Alex Cavalli." After exchanging the normal pleasantries, Dr. Cavalli handed me a little box – maybe just bigger than a deck of cards – and said, "I don't have a name for this yet, but it's my new portable amp. Give it a listen and tell me how you like it."

"Which headphone would you recommend I use?" I asked, not really knowing what the tiny amp could drive. "Well, you were just listening to the HE1000, why don't you try that?" Dr. Cavalli replied. I looked at him quizzically. The HE1000 is not an easy headphone to drive.... I'm thinking this little amp is about to melt in my hand like a chocolate bonbon on a hot summer day. But what do I know? So I plugged it in. 

I remember listening to the all-too-familiar live rendition of "Hotel California" from the Eagles' Hell Freezes Over and immediately thinking, "Oh wow, it actually can drive the HE1000!" Tone was nice, staging was lively and open....

And then the bass hit.

"What in the $%&#@#& #&$@?!?!?!" I'm pretty sure I said out loud. If not, it was definitely written all over my face, because I remember my friend and Dr. Cavalli were having a good laugh. I just listened to the HE1000 on an amplifier the size of a car engine, but this little thing gave it a set of Rocky Mountain Oysters on the low end like I couldn't believe.  I was floored, and it just kept getting better and better as the song went on.

"So how'd you like it?" Dr. Cavalli asked me once I was done, knowing full damn well how much I liked it. I was sold. I finally knew what all these people on the forums meant by the "Cavalli Magic."

That was my first experience with the amplifier that would become the Liquid Spark.

An Amplifier Reborn
Fast forward a couple of years, and after several delays on the Spark, this little amp died before it was ever really born. Dr. Cavalli decided to retire, and Cavalli Audio went the way of the dodo.

But as it turned out, Alex was not quite done yet. Though he was quite finished with the idea of running a day-to-day business, his passion for audio wasn't dead and he wasn't quite content to let good designs die either. He started a dialogue with a couple of companies that were more than happy to handle the business and production angles of getting his amps made. Since then, he has released two amplifiers through MassDrop.com and now he is releasing two more through Monoprice: the Monolith Liquid Platinum ($699) and the Monolith Liquid Spark ($99). It lives!

While the Liquid Spark was originally conceived as a $499 portable amplifier, the new version from Monoprice would be reimagined as a small, inexpensive desktop amplifier. The costly battery was dropped. The ambitious chassis design was simplified. Also, the sheer size, buying power and manufacturing capability of a company like Monoprice helped to drive the price down even further to a mere $99.

As a nice side benefit to that, plugging the Spark into the wall meant Dr. Cavalli was able to replace the voltage rails, giving it more driving power. Much, much more. While the original Liquid Spark offered 350mW into 50 Ohms, the new Monoprice Monolith Liquid Spark offers about 1.35 Watts into the same load. More power for less money? I like where we're headed!

The new iteration of the Liquid Spark arrived in a chassis that somewhat resembled a very small clock radio. It's a mix of gray and charcoal gray with a small light to indicate its power state on the front, along with a power button, selectable gain switch (+3dB, +6dB), 6.35mm headphone jack and a nice-feeling volume pot. On the back side, there is an input for the switch mode power supply, one set of RCA inputs and one set of RCAs outputs that allow you to use the Spark as a preamp. The SMPS is a brick, rather than a wall wart, and is maybe a little smaller than half of the size of the amp itself.

Even with its new, larger chassis, the Monolith Liquid Spark is still very compact overall. And although it's quite basic in its look, it's a handsome little amp that doesn't look like a DIY project. The sound however, is anything but basic.

Unmistakably Cavalli'esque
I've had the pleasure of having extended auditions with every Cavalli Audio amplifier from the last generation, and this tiny little amplifier sounds like a Cavalli amp, through and through. For those who are unfamiliar with the Cavalli "house sound", the amplifiers tend to run a little bit on the warm side, with extremely impactful bass, a warm and robust midrange, and very airy, extended treble. The upper midrange tends to be soft and sweet in its delivery and the treble is rarely, if ever peaky or sibilant, which makes many other amplifiers seem a bit dry and fatiguing in direct comparison. Combined with their generally excellent staging, imaging and detail retrieval, Cavalli amps have inspired a loyal cult following.

The Monoprice Monolith Liquid Spark definitely sounds like a Cavalli amp, no question.

One of the best characteristics of this little amp is the bass. It is very visceral... little tiny amps never seem to be punchy like this. Midbass hits with the authority of a much bigger amp. I can plug my ZMF Atticus ($1099) into this thing and the bass is absolutely slamming with massive authority. It's perfect for rock n' roll music, where kick drums pulse with a solid series of wallops while guitars and basses spring from a burly foundation.

Sub-bass is good, but not exceptional relative to the excellent midbass and midrange. The last octave is slightly rolled off compared to bigger amps and the notes down there aren't quite as resolved or distinct. Still, the Spark does well with electronic music, especially when paired with the Campfire Cascade. The output is plenty satisfactory with a slightly bassy headphone and the very potent upper sub-bass and midbass really give the amplifier a lot of slam, as a whole.

The midrange is absolutely exemplary. Tonality and timbre are warm and sweet, especially in the low midrange, which is on another level relative to anything in the Spark's price class. Vocals are filled with sultry goodness. Honey drips off the strings of guitars. This is absolutely a no-holds-barred "musical" sound. Upper mids are a bit more relaxed, especially compared to amps like the Schiit Magni and JDS Labs O2 (more on that later). This is a very warm and relaxed sound, made more for kicking back and enjoying, rather than analytical listening.

Up top, treble is well controlled. I get some sibilance on the brutally revealing Sennheiser HD800 with tracks that are known to be on the border of problematic, but the Spark is not punishing at all like the Burson HA160 or the O2. I'd say it's truthful, leaning slightly towards forgiving. I would expect a $99 amplifier to either be absolutely punishing here, or, on the other end of the spectrum, be dull and rolled off. Liquid Spark is neither, so that's a very good thing.

Upper treble is a touch less airy and extended than the other Cavalli amps I've heard, which really seem to "open up" in the high frequencies with a ton of extension and ambience. I wouldn't call this a fault, as I don't really miss it when I switch to the Liquid Spark – it's a denser sounding amp, so the change is consistent with the overall sound. There just is a little bit of grain to the sound, which is to be expected for $99, so the amp doesn't quite fully erase itself with pristine open air from the performance space. Still, it can get damn close with the HD800. And at the price, that's pretty stunning.

The soundscape is awesome for the price. Most amps in this range are two-dimensional with three vague blobs representing left, right and center. This amp has a lot more locational specificity than that, with many different degrees from left to right and front to back, which is fantastic. The stage itself isn't huge, but it is still sizeable, well shaped and extends outside of the head. There is actual depth here, which some amps can't accomplish for five or six times the price.

The slight lack of air can occasionally make instruments seem a little closer together than on some more expensive amps, but as I mentioned above, this gels with the overall warm and dense sound of the amp, which means that it doesn't come across as less proficient in any way, just a different sound. That, to me, is the most important part. Because if it wasn't cohesive, it would sound deficient, and that would send me running to another amp. But because it is so cohesive in its sound, it just comes across as a different flavor. In my humble opinion, that's a great thing because you can have it on a desk with several more expensive amps (as I do) and still enjoy it every bit as much for its specific flavor.

The Monoprice Monolith Liquid Spark is also nicely quiet, which allows you to pair it with just about anything, from hard-to-drive planars to IEMs. I plugged in the ultra-sensitive Campfire Andromeda and there was only a slight bit of background noise, which didn't really become apparent until somewhere between 10 and 11 o'clock on the volume pot – which was WAY above the listenable volume level. I was listening closer to 7am or 8am, depending on the source, where background noise was extremely minimal.

Switching to the other end of the spectrum, semi-hard-to-drive planars and high impedance dynamics didn't present any issues. I was actually very impressed with how capably the Liquid Spark drove the HiFiMAN HE500, which didn't seem to be holding back much, if anything. It definitely didn't roll back the bass the way most budget amps do – it was very punchy and enjoyable.

Detail and inner resolution meet and exceed my expectations for the price. As I scale up in price, I expect instruments to sound more specific and unique. On the Liquid Spark, guitars sound great tonally, but picking out the fine nuances of some 1959 Martin acoustic guitar isn't quite as easy as it would be on something truly high-end like the $699 Monolith Liquid Platinum. Does that distract from the enjoyment? Certainly not. That's usually something I really only appreciate as a listener when it is there. In most cases, you have to be really actively listening for it to hear any shortcomings. If you're just sitting back and enjoying the music, the Liquid Spark starts to sound like a bigger, more expensive amp very quickly.

Running The Gauntlet
I compared the Monoprice Monolith Liquid Spark with a number of amps, including the Schiit Magni 3 ($99), JDS Labs O2 ($129), MassDrop x Cavalli CTH ($249), and the more expensive HeadAmp Gilmore Lite Mk2 ($499) and the original Cavalli Liquid Carbon ($599).

The Liquid Spark had the warmest tilt of any of the amplifiers in the comparison with the exception of the original Liquid Carbon. The lower midrange on both the Spark and Liquid Carbon seem to have an extra dose of TLC here, giving guitars and vocals more sense of robustness and a sweet sort of decay that is exceptionally pleasing.

Comparatively, the Schiit Magni 3 and JDS Labs O2 were fairly dry, with a more emphasized upper midrange, and both got fatiguing much more quickly. The Magni 3 had a bit better neutrality overall and a little more deep sub-bass extension, but the midrange felt a little sour or bitter compared to the Spark. Ultimately, I feel this quirk in the timbre hurts the Magni's overall realism, transparency and overall listenability. The Liquid Spark's mids are softer, sweeter, warmer and more inviting by comparison. The midbass is punchy and fun. It's a lot easier to kick back and listen to the Spark, whereas listening to the Magni, at times, felt like a bit of a chore.

This is definitely going to be an area of heated debate, in my opinion, as preference between the Magni and Spark will be highly subjective. The better neutrality/linearity will put some people firmly in the Schiit camp, in spite of the Spark's better overall tonality and musicality. At the end of the day, it's like choosing between an Audeze LCD-4 and a Focal Utopia – do you prioritize the musicality or the absolute accuracy when each one has a slight advantage over the other? That's up to you to decide.

The O2 is much farther behind these two, coming off as being fairly bright and lacking a degree of overall resolution compared to the other two. The sound has a bit more grain to it, and though it is still relatively enjoyable, it's just a little sandpapery compared to the sweet and buttery Spark.

The Spark holds up nicely compared to the more expensive amps, as well. The Cavalli-designed MassDrop CTH is a bit more spacious and linear, while the Spark is a bit warmer and more cozy sounding. While the Spark is the solid state, it does sound a little more tubey in some ways, having that sort of honey-drizzle sweet and thick tone to it. The CTH is more airy and open, comparatively, having more of that tubey "3D" feel. But given the $150 price difference, they are so close that it becomes really subjective. If Alex Cavalli deserves credit for anything here, it's that he was able to crank out some inexpensive designs that can be enjoyed by people of all audiophile budget levels. Even if your everyday amplifier is $3K or $4K, you can absolutely sit down with a Spark, CTH, Carbon or Liquid Platinum and have an absolute blast. The stuff just makes your music sound good.

The Cavalli Liquid Carbon and HeadAmp Gilmore Lite Mk2 are really the point where things start to hit another level, sonically. In direct comparison, the difference in technical prowess starts to come into play. Both are crisper and deliver each note with more assertiveness and resolution compared to any of the aforementioned amps. Still, the Spark is so strong musically that there is a degree of subjectivity to the preference. Without direct comparison things are a lot closer than they have any right to be, given the vast price difference.

The Spark and Liquid Carbon bear a lot of similarity to one another in terms of tonality, the Carbon just does everything better, as one would expect for the price. They both have a bit of a rock n' roll attitude to them – a sort of grit and badassness to the sound that puts a little extra spice on your tunes. The Carbon is just a touch more fleshed-out and robust sounding overall. Individual notes have a bit more thickness and power behind them, especially in balanced mode. Still, the Spark is far meatier than a $99 amp has any right to be. The fact that they are this close is downright ridiculous.

Enjoy the Music.com's Best Of 2018 Blue Note Award winning HeadAmp Gilmore Lite Mk2, by comparison, is a bit more linear, upright and accurate, with a faster pace to it than any of the others. The attack is more brisk, where as the Liquid Spark is very relaxed and flowing, very much like a tube amp. As always, it really lives up to the "Liquid" in its name – the Cavalli amps just let the notes flow out like water.

Perfectly Tuned For Enjoyment
If you didn't notice, there was a prevailing thread across all of the comparisons as I put the Liquid Spark through the gauntlet. This amp is one enjoyable listen. While it can certainly hang on a technical level – surpassing the O2 and trading blows with the Magni – it was never got outclassed in the area of pure musical enjoyment.

As soon as my analytical hat came off, the sweet, intoxicating sound of the Spark always brought me back. I didn't want to go back to the other amps.

The midrange is where the music is, and the problem I have with most entry-to-mid-level gear is the midrange absolutely sucks. It is either bland, stiff, lifeless cardboard. Or it is bone dry with a bitter aftertaste. Or it's overly veiled and claustrophobic. The Monoprice Monolith Liquid Spark is none of those things. It is sweet, evocative, riveting and full of life.

For that reason, I would say that unless you are a purely analytical listener, the Monoprice Monolith Liquid Spark makes a fantastic addition to any audiophile collection. It is quite capable for the $99 price tag, but what it does musically is absolutely exceptional. No matter what level audiophile you are, from a budget level beginner to a bargain hunter, to someone on a flagship-only-audio-filet-mignon diet... I highly, highly recommend giving the Liquid Spark an audition, because this little $99 amp will absolutely put a smile on your face. It is just pure fun.

Additional Equipment Used in This Review
Sennheiser HD800
Sennheiser HD600
MrSpeakers AEON Flow Open
ZMF Auteur
ZMF Atticus
HiFiMAN HE500
Grado SR225i
Campfire Andromeda
Campfire Vega
FiiO FH5
Westone W60
Wells Audio Milo Headphone Amplifier
Glenn OTL Tube Amplifier
Cavalli Liquid Carbon
HeadAmp Gilmore Lite Mk2
JDS Labs Objective 2
Massdrop CTH
Monoprice Monolith Liquid Platinum
Schiit Audio Magni
iFi iDSD Black Label
Chord Hugo 2
Schiit Audio Yggdrasil
DanaCable Lazuli Headphone Cables
DanaCable Onyx Interconnects
DanaCable Trustream USB Cable
Wireworld Electra 7 Power Cables
PS Audio Duet Power Conditioner
Roon
Amarra 4 Luxe
Tidal Hi-Fi

Specifications
Type: Solid-state stereo headphone amplifier
Rated Output: 1.35 Watts @ 50 Ohm 
Output Impedance: <0.1 Ohm
THD+N: 
1VRMS (20mW) - 0.007% THD at 1kHz both channels. 
5VRMS (530mW) - 0.035% THD at 1kHz both channels
Dimensions: 4.5" x 3.75" x 1.5" (WxDxH)
Weight: 252 grams
SMPS: 36V @ 1.5A
Price: $99

Company Information
Monoprice, Inc. 
11701 6th Street
Rancho Cucamonga, CA 91730

Voice: (877) 271-2592
Website: www.Monoprice.com