I have been using LCX for a month and generally speaking this little box is really enjoyable. Here I would like to share my experience with MDers. To save your time, I won't write long paragraphs with beautiful terms like those "professional" reviews, everything will be just plain and simple (and intuitive)
My gears connecting to LCX : Alienware Alpha PC + M2tech Hiface Evo two D-D interface (with Evo supply two linear power) + M2tech Young DSD Dac (with teradak linear power). All the cables and cords are not luxurious yet adequate to pair with all those audio machines. Music source is Tidal (HiFi and Master).
Before I start, I should remind that although thanks to the sweet price LCX really looks like a cheapo, you still need to remember the original Liquid Carbon was not an entry level amp; and, maybe (just maybe) LCX is not as good as the original due to its low manufacturing costs, a better-than-entry-level DAC is still recommended. In short, don't let your $100 DAC nerf your LCX. (if I incorrectly use the term "nerf" please forgive me)
LCX's sound is pretty straight forward and neutral, which means it won't cover or color your DAC's sound and it will directly show you your DAC's ability. So, if you happen to have a DAC with really poor performance, LCX won't make it sound better.
- with Sennheiser HD800S (balanced, high gain) : well, LCX (and even the original LC) is not supposed to have enough juice to feed the flagship level HD800S, however, turns out that HD800S does not sound awful with LCX. With many other Amps in this price range, HD800S sounds thin and harsh while with LCX HD800S sounds full-bodied. But, can we conclude that LCX is a good match for HD800S? Not really. Though the sound is acceptable, it still lacks transparency and sound stage, and is not airy enough. Schiit Mjolnir is much better than LCX when paring with HD800S.
- with Beyerdynamic T1 1st gen (balanced, high gain) : here is another "not supposed to". Based on the specs, LCX doesn't have enough output power to push the 600 ohm cans. Here is another however. However, T1 dose not sound awful as well. Still full-bodied (with a little harshness). But still not transparent, wide and airy enough. So, here is another acceptable.
- with Grado GS1000e (single-ended, low gain): GS1000e is really picky and hard to tame so it's really tough for LCX. However (the 3rd however LOL) LCX is not an immediate loser. GS1000e does sound relatively harsh with LCX but if you don't listen to those contemporary EDM tracks with the overly bright synths you should be fine. All the acoustic instruments still sound sweet. But I won't give LCX the 3rd "acceptable" badge this time because LCX doesn't make GS1000e sound equally acceptable for various genres. The Cypher Labs Sustain 84 is much much much better than LCX for paring with GS1000e (of course 84's msrp is much much much higher).
- with Focal Elear (the original Elex, balanced, low gain) : Elear is famous for "easy to drive". But here we need to understand the meaning of "easy to drive" correctly: Elear doesn't require a high power Amp but it dose need a high performance DAC; "easy to drive" doesn't mean you can throw Elear to everything (for instance your iphone) and expect a stunning sound. So if you have a decent DAC (IMO, the baseline for Elear is m2tech young dsd or mytek 192 or chord hugo or any DAC near or above $1000), with LCX Elear can really shine. Many other balanced amps are too powerful for Elear and they usually make Elear sound too "excited", which means Elear could lose its most adorable characteristics: sweet, fluid and effortless. Whereas the low-power and neutral LCX has the ability to keep Elear's sweetness and effortlessness and at the same time add dimension and depth to its sound. Thus I would like to say LCX is a good match (though maybe not the best) for Focal Elear/Elex.
- with Fostex Thx00-Purple Heart (single-ended, low gain): another easy-to-drive cans. The situation is pretty similar to Elear's so I won't repeat.
- with AKG K701 (single-ended, high gain): another picky monster. Luckily K701 is not as wild as gs1000e so LCX works well with it. Though K701's high frequency still sounds a little harsh but the overall performance is better than decent. K701 sounds pretty balanced with LCX and doesn't show any significant sign of lacking power. And here I discovered a small interesting bonus: K701's female vocals are so so sweet when paring with LCX whereas the much more expensive sustain 84 doesn't add sweetness to K701's female vocals.
- with Sony MDR-Z7 (balanced, low gain) : Z7 has really mixed reviews and when I used it with my pha3 I thought I would never like it because Z7 sounded like a thick lump of overly sweet and fatty cream that could make me feel nauseous. However when I connected Z7 to LCX an unexpected miracle happened. No more overly sweet and fatty, Z7 showed its hidden muscles and sounded like the mixture of Philips Fidelio X2 and Beyer T1. Personally this type of sound is more favorable to me but if you like the creamy sound of Z7+Pha3 I think you should avoid LCX (or maybe also avoid Young DSD) because it could dramatically change Z7's sound.
- with those portable headband headphones (such as Master&Dynamic Mh40, Sony Mdr-1a, Senn Momentum, you name it): well, good good and good.
- with studio monitoring headphones (such as dt770 pro, sony mdr 7520, Krk Kns8400, Audio-technica M50x, etc) : good and not good. Good means LCX is so neutral that you could still use it when you are mixing or recording. Not good means LCX won't add any lovely flavor to your flat and plain studio phones so if you think your 7506s are too boring LCX may not be able to help you.
Okay, so much for that. Hoping the text is not so vague. As a non-native speaker I tried my best : )