Monoprice Liquid Spark Headphone Amplifier Review: End Game?

Our readers have asked me a few times to do a series of articles on high quality audio. Where to start?, what do I need? is it expensive? This isn’t going to answer all those questions completely but it is a part of the puzzle. In the near future I’ll be posing a series of articles and videos to answer all those questions.

In The Box

I normally start all my reviews with the unboxing experience. However, I’ve learned when it comes to amplifier the experience is rather lacking luster. They are often packaged in a plain box, normally wrapped in plastic and there is some type of power brick.

Not much to see here, Amp and laptop style power brick.

The Monoprice Liquid Spark by Alex Cavalli is no different. We’ll be skipping the unboxing and going straight into the build. The only thing to point out is the power brick included with  Spark is similar to a laptop. The cord that plugs into the outlet is a normal size and won’t take up extra space on a power strip.

Power button, 1/4 in Audio Output, Power/ Ready L.E.D, Gain button and Volume knob.

Build Quality

The Liquid Spark is solidly built. The exterior is entirely metal, no plastic case here (I’m looking at you JDS Labs). On the front, you’ll find the power button on the left, next to that is a plastic 1/4in headphone output. Most, if not all amps in this price range will have plastic outputs. I won’t ding the Spark for having a plastic output. Next is the gain button and finally the very satisfying to turn volume knob.

On the rear, you have 2 sets of RCA jacks. One set is marked with I (input) and the other set is marked with P (preouts). Lastly, we have the 36v 1.25a power input.

Analogue Input, Pre Amp Outputs, and Power in.

As a package, the Liquid Spark is very well assembled. All the connections were firm, in other words nothing wiggled or felt loose when plugging or unplugging connections. The knob on the front is one of the nicest that I’ve used in a while. It’s not too small or too large, it has just the right amount of tension. The case is nice too, however, the look is bit subjective. It might not be your style, but its not a boring black box at all. If I had to nitpick anything the push buttons for power and gain seem like they may be slightly off-center. Again this is me nitpicking if I had to find something to complain about. All said the button alignment in no way affects the use or sound of the amplifier. So it really doesn’t matter in the grand scheme of things.


Similar to most amps especially those around the $100 price range, the list of features is slim. However, I want to point out the main selling point of any amp is going to be the sound quality, and power (more on this later).

Getting back into the features, the rear as I mentioned earler has a set of pre-outs. This means the Spark can be used as a preamp if you have a pair of powered speakers with RCA input. This would allow you to control the volume with the knob on the spark and remove the need for extra equipment (preamp) on your desk. You may have noticed that there is also no button to swap between the preamp output and headphones. The Spark will automatically swap to the preamp when the headphone jack is unplugged. Pretty slick! Other than that the Liquid Spark is just a really good headphone amplifier.


liquid spark
Monolith Liquid Spark  by Alex Cavalli:
Signal-to-Noise Ratio108dB (ref. 1 Vrms input / 2 Vrms output @ 1kHz)
Crosstalk–73dB (ref. 1 Vrms input / 2 Vrms output @ 10kHz)
THD+N (both channels)1 Vrms (20mW): 0.007% THD+N @ 1kHz
5 Vrms (530mW): 0.035% THD+N @ 1kHz
10 Vrms (2.12W): 0.065% THD @ 1kHz
Output Impedance< 0.1 ohms
Gain+3dB or +6dB
InputUnbalanced stereo RCA
Headphone OutputUnbalanced stereo 1/4″ TRS jack
Preamp OutputUnbalanced stereo RCA jacks
Output ProtectionDelay and offset protection
Dimensions4.6″ x 3.7″ x 1.5″ (117 x 94 x 38 mm)
Weight9.6 oz. (271g)
spark specs

Performance (TL;DR)

Everything that I’ve said so far means nothing if the Liquid Spark doesn’t sound good. Well, I’m here to tell you that it sounds better than good. Monoprice worked with Audiophile-grade audio legend Alex Cavalli to bring a few of his amp designs to market. Liquid Spark is one of them. It started in 2016-2017 as $499 portable amp but ultimately became a desk amp after Dr. Cavalli decided to close the doors of Cavalli Audio and actually retire. Monoprice and Dr. Cavalli decide to ditch the expensive batteries, make it slightly larger and add more power while they were at it. All of these changes along with Monoprice’s ability to build at scale dropped the price from the original estimated price of $499 to around $99… Crazy right! So stop reading and buy one now. Liquid Spark

It’s hard to believe you can get an amp this good for around $100.

How is it this good and this cheap

The best place to start is with the name. If you’re familiar with amplifiers from Cavalli audio then you know most if not all of them start with the word liquid. Liquid is the term used to describe the mids because they flow like water(liquid), another trait of Cavalli’s house sound is slightly rolled off highs. Both of these traits together don’t really color the sound but you do get a sound that has the slightest hint of tube-like warmth, and treble that doesn’t become harsh.

I know that all might seem a bit confusing. So let me attempt to explain it in more musical terms. Cavalli audio has a house sound like most other audio companies. It’s a signature tuning style that gives their audio products the same sound signatures. Cavalli Audio is known for fantastic full-bodied fluid mids. Mid-range sounds are going to be the life of a song, vocal and instruments are typically in the mid-range. I could argue that mids are the most important frequencies if you want your audio to shine… So the Liquid Spark definitely checks the mid-range box.


Grado are known for having a very bright and lively sound. They pair fantastically with the Liquid Spark.

The next part of the Cavalli house sounds is the treble that rolls off slightly just around that range where things begin to sibilant and harsh. If you don’t know what sibilance is, it’s when high frequencies become raspy and harsh with sounds that sound like “s” and “t”. Sibilance if you can stand it leads to listening fatigue, which is obviously something that you don’t want.

Let’s put those 2 things together with decent lows and you get an amp that sounds really transparent, it doesn’t really change the sound of the original recording as the artist intended. It breathes life into it, which is something that so many other amps can’t do.

When it comes to power the Liquid spark can output about 2.4 amps max which is WAY more than you need for any headphones, even the hard to drive planar. I found that at low gain I could turn the volume knob up fully with no audio playing and get no white noise/ static. On high gain I could get some around the 3 o’clock position with sensitive IEM. Keep in mind I could never listen to any of the headphone I tested with the volume that high. Wearing less sensitive non IEM headphones like my Grado’s I couldn’t hear any noise even on high gain.


While I’m talking about headphones now would be a good time to explain pairing or synergy when it comes to amps and headphones. Most amps and headphones have individual sound signatures. Sure, some headphones and amps from different manufacture may sound really similar but more often than not they will have a sound that is their own. Some headphones like Grado and IEM like the Tin T2 Pro’s have a really bright, lively sound or what some may call sparkly. It gives them a really fun and alive sound but that sound can become too much very easily depending on the song, the amp or DAC.

The Tin HiFi T2 PRO that have enhanced highs are a perfect match to Liquid Spark.

This is where Liquid Spark and pairing come together. The lively mids of the Spark with its slightly rolled off highs, combined with a headphone that has fantastic mids and highs that border on to much, is a match made in heaven. The result is nothing short of amazing. You get this vivid, full of life clean listening experience that has to be heard to really appreciate.


This could, of course, work the other way as well. Using Headphones that are substantially lacking in treble in combination with Spark could result in a really bland sound. Deal-breaker? I doubted, but it’s worth saying. I’m about to move on but I want to clarify what I just said. The Spark really only knocks off that very edge where the highs become nasty and rattly on all but the very best headphones. So yes, it’s not likely going to destroy or negatively affect the sound on most headphones. However, if you’re unlucky enough to own a pair of headphones where the treble is so far gone and the mids are crazy the Spark might not be the best paring.

Final Thoughts

Let me wrap up this already long review by saying right now the Liquid Spark is the amp in my personal desk set up in the TLR office. We have other amps I could use but for me, personal the Liquid Spark maintains the honesty in the music while bringing life to it. I’ll admit that we like the sound so much that another member of the TLR team bought a Spark as well. This is not only one of the best amps that you can buy around $100 it’s one of the best amps that you can buy for under $400.

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  1. I own Grado 125e headphones and have ordered a Liquid Spark amp….Just read your review and feel even better about my decision….been using a Project 2 headbox, which sounds a little too bright to me. Hope this new combo sounds as good as your review suggests.


  2. Re; Grado 125e & Liquid Spark pairing…My initial impression was a bit ambivalent.. I felt the strings in a classical orchestra took on a “Ektachrome” character regarding the contrast and colour. After a few hours of listening either I have adjusted to the sound, or the sound has mellowed a bit. I think its the latter. After all the accompanying literature does suggest that the amp need about 100 hours before it settles down. In any case ,it certainly gives you everything on the CD…including room noise…I could hear someone walking around in silent passages on the RCA recording of “The Reiner Sound”…I never noticed these before. Overall I feel the headphones and amp work well together and I’m not tempted to return to the Project headbox 2 I had been using. I think your review was spot on.


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