update regarding the DDCs
I've tried Denafrips Iris, Singxer SU6, Douk U2 Pro with Crystek 957, Matrix X-spdif, Audio GD DI20 (non HE)
could not get a Sotm TXusb Ultra in time for the comparison, i'll update if it's mind blowing or something life changing
for consistency i only used a Singxer SDA6 Pro Dac (really competent DAC using a well designed input stage and Crystek 957 clock + AKM4499)
tried both
IEM (Singxer SA-1 > UM Mest 2 CIEM / Fiio FH9)
Speakers (Pass Labs INT-30 Integrated > Custom Speaker using Satori Textreme & Bliesma Beryllium Tweeter)
for comparison i had my Sotm SMS-200 Neo + SPS-500 Combo as it's my best other Streamer + PS combo
I also tested several power supplies with the Zen (IFI Elite 12V / Sotm SPS-500 12V Setting / Sbooster BOTW without the little dongle upgrade / Uptone / Ipower / Ipower 2 / Ipower x / + dc purifier in combination with other power supplies
DDC:
to sum it up in a few words, Ifi left very little on the table to "improve" of the various DDC i tried none was just simply "better" for eg cleaner sound, bass etc
DDCs amounted to tonality differences rather than "improved" SQ, if i had to pick one i'd probably say Denafrips IRIS, I'm probably selling a couple of these DDCs and try out a Denafrips Gaia just because i've heard so many good things about it, overall IRIS made the sound a bit softer yet more pleasant on modern pop music)
I'm all about the last 2% but Ifi did put out a device that does not apparently suffer from the same gremlins as other digital products so not much left on the table
PS:
of all the power supplies the Ifi Elite & Sps-500 were my favorite, in the end i picked the Elite 12v for the Zen, btw i love the fact Ifi included a really good dc cable with the Elite, it's OHFC Copper
here the difference i heard was fairly obvious, both improved the bass in extension and impact and overall sound is a bit cleaner (the ac power in my room isnt clean as it shares a circuit breaker with some appliances, so i use a PS Audio PP3 AC Regenerator, for this test though i plugged all devices into a simple Furman unit)
I went with the Ifi Elite simply because it was cheaper and had a better DC cable
Sotm SMS-200 Neo + SPS-500:
comparing the Zen + Elite combo, the sound is different, Zen presentation is very clean / precise and Sotm is "smoother / softer"
ultimately i like the Zen on my Speaker setup and for IEM it's really a toss up, Zen performing better with properly recorded / mastered music and Sotm for lower bitrate stuff
hope this helps and please remember i'm just a random guy on internet saying all these things, please do more research before spending any money