This is a review and detailed measurements of Massdrop's Alex Cavalli Liquid Carbon X headphone amplifier. It is on kind loan from a member. I think the retail price was $299 but since the drop is over, I am not 100% sure. Someone should comment if that was not the case.The Liquid Carbon X is an attractive headphone amplifier. It manages a luxury feel despite its low cost. Here you see it below the new Topping DX3 Pro dac and headphone amplifier (review to come).The Liquid Carbon X is covered in semi "rubberized" paint which while feels nice, tend to show any dirt or dust. So keep a rag next to it if you want it to look good.As you see in the front, it has both balanced and unbalanced connections. Same is the case in the back where there we have both balanced XLR and unbalanced RCA connectors.Overall, it is a thumbs up on design, look and feel.For power, it comes with what looks like a laptop switching power supply, producing whopping 30 volt output! I think this is the highest voltage power supply I have seen on any desktop audio product.Let's see how she does in measurements.Let's start with our usual dashboard measurement in "unity gain" (2 volts in, 2 volts out):This is not much to write home about. It means that it underperforms most DACs and becomes the dominant source of distortion given the SINAD of 96.For this review, I will be comparing the Liquid Carbon X to Arcam rHead since it has similar features. So I decided to set the levels such that it compares to my review of Arcam rHead and compare:Yuck. We are not in even in the same neighborhood. Despite rather high level of output power, the Arcam rHead manages a SINAD of 105 whereas the Liquid Carbon X sinks to just 70 dB!Measuring power at 300 ohm we see the same situation:The Carbon X starts to lose its breath around a few milliwatts. It crosses the Arcam distortion curve at 11 milliwatt while the Arcam cruises to higher power at even lower distortion @120 milliwatt. Noise level is lower though throughout that range.Oddly, the noise advantage goes away when we switch to 33 ohm load:Same power disparity remains with the Carbon X producing just 0.26 watts relative to rHead's 1.1 watt.The only power ratings from Massdrop are at 50 ohms so let's see how the Carbon X does in both single-ended and balanced:Massdrop's spec for single ended is 0.7 watts. I am not remotely getting that. I always drive both channels at once so maybe they measured one channel at a time.Same is true of balanced output in that it is half as much of Massdrop spec. That aside, you do get a lot more power in balanced at the expense of higher noise. Trade off is worth it though.Output impedance is essentially zero which is excellent:Finally let's look at channel imbalance relative to volume control position:Again, Arcam rHead leaves it in the dust with near perfect channel balance.I used the setup in the picture with Topping DX3 Pro driving the Liquid Carbon X at full level. I started with my Sennheiser HD-650 headphones. Here, up to about 2:00 o'clock in volume control, the sound was fine and reasonably loud. After that, it became higher pitched and somewhat muddy, indicating onset of distortion.I then switched to HiFiMan HE-400i and given its lower impedance, the unit became fairly loud at 12:00 o'clock. Past that point though, distortion again became obvious with emphasis in higher frequencies and generally unpleasant.The Massdrop Cavalli Liquid nails the industrial design and branding. The marketing department gets an A+ here. Alas, from engineering point of view, this is an average effort. Power levels are modest as desktop products go.Subjectively, the Liquid Carbon X simply does not have enough clean power for my taste. The purpose of such a large desktop units should be to have ample amount of power to throw any headphone at it. That simply is not the case in single-ended mode. The amplifier distorts before the headphone which is no good.I don't have a balanced headphone to test with it. That should be a more satisfying experience given the higher power output.As I have noted, the Arcam rHead performs much better. It is much more expensive if you pay full list price but you should be able to find it on the used market for same cost as the Liquid Carbon X. Another choice -- if you don't mind the high output impedance -- is the Aune X7s. It is the same price at Liquid Carbon X but with a lot more clean power.In summary, whatever magic people assume behind this branded product escapes me, both in engineering and subjectively. Nothing is badly broken but there simply is not enough "oomph" to make it for me. So I can't recommend it.As always, all questions, comments and criticism is welcome.-----If you like this review,using Patreon ( https://www.patreon.com/audiosciencereview ), or upgrading your membership here though Paypal ( https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054 ).