Ok...Just returned from a demo session of the 1Z, with a comparison against the 380CU. But before that, I thought that I shd start with some extracts from the conversation I had with the engineer behind this project with regards to the philosophy and design choices behind the player.
From what i gathered, he said that the lack of a wifi/streaming feature was a deliberate choice, as this player was meant to reproduce music in its optimal form. Hence it was stripped of any and all unnecessary components that did not add to that goal as each additional component in the player casing would pollute the final output. So in his view, if you rely on streamed music, this is not the player for you.
Secondly, the choice to go with a pure copper chasis was because its use as a grounding point offered the the player the best sonic performance. Holding the player in your hand should not affect the sound, as the impedence between your hand and the player would be too high to to matter.
Third, why the choice to use Kimble cable for the internal wiring instead of, say, pure silver or even gold plated silver? It was interesting to note that both cables were the same , although they were sleeved using different material (and hence the different colour). His team went ahead with kimble pure copper cable (or was it SPC? not really sure due to my meager japanese proficiency), as it added the most body to the sound. They experimented with using pure silver (they said it made the sound too harsh), SPC and so on, and they found that copper for the jack wiring offered to them, the sound that was closest to their ideal.
Lastly, we talked about the power output from the 3.5 and 4.4mm. He admitted that the 4.4 was way more powerful (the aide said that the balanced was 4x more powerful, but I think I heard wrong). My follow up question was impedence matching, since CIEMS and headphones have very different power demands, but they insisted that the player was 'universal' in its application, and that BOTH CIEMS and headphones will be more than well served by the 1Z on both single and balanced. However, he did recommend that CIEMS stick to the single end side of the 1Z.
Ok, now for sonic impressions.
I spent a good 15-20 mins demo-ing the unit, with side by side comparisons. The SD card in the Sony player was a Sony Audiophile card (64gb), paired with a DHC type 2 litz Fusion wire 8 wire (my reference cable, most people find it lifeless), using a Empire Ears Omega CIEM with a tweak made to emphasize resolution as opposed to the bass regions.
Sonic characteristic (female vocal songs):
I found the 1Z alot more full bodied in the mids and the lower bass regions. Vocals sounded more weighted, and powerful. The bass hit harder, and had more rumble. The 380CU sounded more reference, and even thin (if you could call the CU 'thin') in comparison to the 1Z.
Staging (live performance recordings):
The 1Z had a slight edge in its spatial imaging, with the CU was more defined and focused in its presentation. If the 1Z made the song resemble a concert hall experience, the 380CU made it sound like a well engineered studio room.
Resolution and technicality.
This is where the CU, overtakes the 1Z, much to my surprise. The CU was, hands down much more resolving than the 1Z. The bass texture was way less boomy and had very minimal bleed in the CU, while in the 1Z the lower bass was slightly boomy and spatially bled into different areas. Vocals, was also slightly unfocused and somehow struggled to extend as naturally as the CU. This made the 1Z, as strange as it sounds, sound a little unnatural and awkward. This, unfortunately, added a slight 'veil' to the sound, and made it sound a little muddy compared to the 380CU.
CONCLUSION
Tl;DR. The 1Z certainly is a flagship products that will appeal to a large majority of the market. Most people will find that full bodied, coloured sound extremely appealing and engaging. Coupled with its higher power output on the single and balanced end, it will serve a large majority of the audio community that straddles both iems and headphones very well.
However, as a person who only uses CIEMS, and intends to expand into a speaker set up, the 1Z offers little reason for me to shift over from my 380CU. The CU is simply more resolving when one uses sensitive CIEMS that responds to the smallest of changes and details, and I feel that for a flagship audiophile product such as this, this is one area that the 1Z cannot afford to fail in.
