Questile CMA18 and FiiO K19 in the house. Here are just a few impressions for those who want to know. I don't want to be detailed. Here are some impressions as they came into my head, so they are not systematic, but rather mixed up. If you have more specific questions, just ask.
What makes the N30 so special compared to the CMA18 and K19 is the timbre. Even in SS mode, it is very realistic, lively, vivid and emotional. Bass and mids sound lifelike/authentic, whereas with the others they are comparatively more artificial. Another impressive feature of the N30 is the depth of the stage and general holography. It is clear to hear that the music is multidimensional. I hear a special, unique plasticity, bass and mids stand out. The scene is more forward and this is due to the fact that the N30 has more tone weight. The CMA18 has less weight in the low mids and is brighter in the upper mids. In this respect, the N30 is smoother, but at the same time more detailed in its macrodynamics. In terms of microdynamics, the K19 has the upper hand, but I'm not sure about the CMA18. Perhaps the CMA18 has a little more instrument separation, as the note is not as thick as the N30. There is more space between the instruments compared to the N30, but that would probably be all. The N30 has more texture, especially in the bass and mid range. Taken together, the N30 is absolutely unbeatable for timbre.
Both the CMA18 and the K19 are amazingly good for the price. I bought the K19 for gaming with the PC and Playstation 5. I was very surprised by the technical capabilities of this thing. I really didn't expect anything and I had to realise that it undoubtedly beats the N30 in analytical listening. It reminds me a lot of the DX320Max, but without the weakness/dealbreaker I felt compared to the N30 in terms of bass (little texture), mids (recessed) and stage (narrow). So the K19 definitely has texture in the bass range, the mids are more at the front and the stage is significantly wider than the N30 (but which has more depth). The K19 has less note decay and less fuller low mids than the N30. Both areas can be separated more clearly so that more information can be extracted from the music.
The K19 and N30 are very complementary and per se, i.e. really at a very high level in their respective categories. The K19 wins for neutrality, analyticality and technicality. The N30 wins for musicality, emotionality and immersion. For gaming with the Playstation 5, there is undoubtedly no better device on the market that is UAC 1.0 compatible. In contrast to the N30, the K19 also has no (notably) delay (I'm quite sensitive here), so unfortunately the N30 is not ideal for the PC.