Review - Drop Cavalli Tube Hybrid (CTH)

(Long Term) Review - Loxjie P20

Review of the Loxjie P20




Between reviewing new items that arrive, I would like to make some time to go over equipment and items that are part of my daily chain, giving you an idea of what I use on a day to day basis. 

Although these are not meant to be specific reviews, I do feel that it will help give an idea on my personal preferences and also provide additional reference points that can be used in my reviews.

Not long ago, I posted my opinions on the Beyerdynamic DT1990 Pro after 18 months of use. Unfortunately I did not get chance to record a video for that yet, but you can find my opinions and review here: Beyerdynamic DT1990 (after 18 months)

Today, I want to talk about one of the amps I use regularly, the Loxjie P20.

Let me point out that this is not my most used amp, that would be my JDS Labs Atom(s), but I do give it a lot of time and it is part of my desk set up at work where I do the majority of my casual listening. The reason I am starting with the P20 is because the Atom(s) have their cables pretty much fixed in place and I don’t have time to get them out at this moment. I will make time for the Atom soon.

About the Loxjie P20…

The P20 is a fully balanced hybrid amplifier that was released around 2 years ago (maybe a little more) and one of the most interesting features is its price. It sells for around 100€ and for that price, you get a very nice little amp.

Loxjie is a brand that is owned by SMSL but is manufactured elsewhere, or at least it was when this amplifier was released, it is difficult to keep up with manufacturing processes and locations in China. 

The P20 was well regarded when it was released, they sold quite a high number of them, as it offered good performance for a reduced price and was a cheap way of entering in to the balanced amplification world. The performance is still good today, it hasn’t gotten any worse, but I’ll talk about that a bit more in a moment.



Build quality…

The build quality of the Loxjie P20 is very good. The case is completely made of metal, with a good finish and no noticeable flaws.

The volume wheel, which also functions as a push button selector, has a good feel to it and has not given me any issues in the time I have owned it. It uses a digital volume control which avoids channel imbalance even at the lowest volumes.

The connectors used are by a brand named Zwee. This is a brand I have never heard of and whilst they are not by a known brand such as Neutrik, they again seem to be of good quality and have not caused me any issues. 
The screen is not the best, it is a simple 3 digit small screen with blue digits, but it serves its purpose and, due to its simplicity, is readable from quite a distance (depending on your eyesight).

There are purple LEDs located under the tubes which I am not a huge fan of but that is personal preference and they are not bright enough to be considered annoying (in my opinion of course).

The power supply is external but is not the typical brick that connects to the socket. The PSU for the Loxjie is of the type that has a cable before and after the transformer, which I prefer personally as it takes up less space and is more manageable.

With regards to faults and issues, I can only remember reading of one case where there was a unit with a whining sound through the output which was traced down to being caused by the screen (disconnecting the screen fixed the problem). There may be others that have had issues but I don’t remember reading about any.

Functionality…

As I said, this is a fully balanced hybrid amplifier. Hybrid means that it uses tubes in the preamplifier stage, while using solid state for the actual amplification. The idea behind hybrid designs is that it gives you the benefits of both worlds, tubes and solid state. There are certain headphones (such as planar magnetics amongst others) that do not work well with tube amplifiers and the hybrid design is supposed to address this by giving you the “flavour” of the tubes in the preamp stage while using solid state amplification to avoid these issues. There are far more details to go into about hybrid vs tube vs solid state, but that is not something for this review.

The fully balanced part means that it uses amplifiers for each channel that do not have a shared reference to ground. As a simple way of looking at it, a separate amplifier for each channel.

There is a lot of debate and (mis)information regarding balanced amplification for headphones and the benefits, but again, I am not entering into that discussion here.

The Loxjie P20 offers both balanced (XLR) and unbalanced (RCA) inputs, along with balanced and single ended outputs, these can be selected from the menu (it’s as simple as pressing the volume wheel and then turning to select. You have the option of ou1 and ou2 (for balanced or single ended outputs) and in1 and in2 (for balanced or unbalanced inputs).

As far as functionality, that is it, it’s pretty simple.



Sound and performance…

I am afraid that I am a bit of a hypocrite when it comes to amplifiers. Due to the nature of how I have been involved in the music and audio scene, I am of the belief that an amplifier should do its job without you being able to tell it is there. In other words, that an amplifier should just amplify whatever it receives without colouring it.

But at the same time, I am someone who strongly believes in EQ. I do not follow the “how the artist intended” theme, as I listen to music for my own enjoyment, and if EQ is needed to make it sound as I want, then so be it (you can read more about my opinions on EQ  and how the artist intended it here: EQ - Good or Bad?)

In the case of amplifiers that aren’t transparent, which is not just limited to tube or hybrid amplifiers, then I feel that the “colour” they give to the sound is like having a fixed EQ built in. This “fixed EQ” can result in something that is good for some people and bad for others, good for some tracks and bad for others, good for soom moods and bad for others, good for some headphones/speakers and bad for others, or just a combination of any and all of those.

In the case of the Loxjie P20, the change between a solid state amplifier (such as the JDS Labs Atom, which is of a similar price and sits next to the P20) is not night and day, well, not always anyway. The colouration of the sound by the tubes in the P20 is very slight and is nowhere near as noticeable as on other amplifiers that use tubes, but it is still noticeable and changes to the tubes installed do make a difference.

I haven’t tried a lot of different tubes in the P20, maybe 4 sets, but I liked the ones I currently have in (I believe they are the GE5670 Triple Mica by Western Electrics) and those have stayed in it for the majority of the time I have had it.

If I had to explain how this amplifier (with these current tubes) changes the sound, I would say that it makes it sound a little warmer (not by increasing the bass but by smoothing it out a little) and at the same time gives a little extra width to the sound. Now, these are completely subjective descriptions and to be honest, as I said, the change between this amp and a solid state is not overly dramatic.

One very positive thing about the performance of this amplifier is the background noise, which is zero. Even with sensitive IEMs, there is no background noise to be heard, which is quite a feat for a balanced hybrid amplifier at this price point.

However, one of the negative points is the output impedance of the amplifier. I cannot remember what the output impedance is exactly but I seem to remember it being around 40 Ohms, which is very high.

For those of you that are reading this and are not familiar with output impedances, a high output impedance can change the way headphones and earphones sound when connected to the amplifier. This change in sound is unpredictable and can be anything from very bad to very good, and anything in between.

I like to try out IEMs on the P20 and as the majority of IEMs are low impedance, this means that the outcome of the connection is completely random from one IEM to the next. There are IEMs that I really liked connected to the P20 (such as the Blon BL03) and others that I really disliked (such as the Urbanfun YBF).

For higher impedance headphones, the outcome is more predictable but can still depend on personal preference and headphones used. For example, I prefer the HD6XX (300 Ohms) on the Drop Cavalli Tube Hybrid (in my home chain) but prefer the RY4S (also 300 Ohms) on the P20.

One more thing that I need to point out about performance is the single ended output of the P20. For some reason, the sound quality of this amplifier is nowhere near as good when using it in single ended mode. When I first got the amplifier, I thought I heard a large difference between the balanced and unbalanced inputs but that turned out to be user error (I had an issue with a cable I was using) but the outputs are very different between balanced and unbalanced. 

When using the SE output, the sound is far more congested, not as clean, and just sound pretty crappy in general. When switching to the balanced output, everything becomes a lot cleaner and better overall.



Conclusions…

The Loxjie P20 has been in my chain at work for a long time now and I have tried it with many headphones and IEMs that have been through my hands.

I don’t use the single ended output as I find it to deteriorate the sound of anything that I plug into it, but anything that I am able to run balanced (headphones, IEMs, etc.) I have plugged in to the P20 at some point.

Some of the results have been great, other results have been mediocre and some results have been down right terrible. However, this is due to the output impedance that has affected some headphones/earphones in negative ways.

I feel that the Loxjie P20 was a very good purchase for 100€ and that it is a very well built unit capable of doing good things with headphones that pair well with it. The tubes are noticeable, as you can tell a difference between tubes when swapping them, but it is not overly “tube flavoured”. I wouldn’t say that the P20 is a good amp to understand what a tube amp sounds like, as it is still very clean, but it is certainly something that I enjoy having around.

There are more balanced options available now (although I am not sure if the P20 is still the cheapest option) and there are tons of low cost hybrid amplifiers available on the web from many brands (known and unknown) but I wouldn’t hesitate to pick out the P20 from amongst them.

In comparison to the Massdrop Cavalli Tube Hybrid (which I will talk about another day), I do prefer the Cavalli, however, there are certain things that the P20 is better at. For example, while the MCTH has a much lower output impedance, making it more predictable, the background noise is slightly more elevated and can be noticed on sensitive IEMs.

In the end, for the price,  I feel that the 100€ Loxjie is something worth having around even if you don’t use it a lot.

SenyorC