Hmmm, I think the 3.5 is for sensitive IEMs, but the better IEMs actually like more power.
Maybe due to having Electrostatic elements.
Yet the Sony distortion specs are decieving.
The distortion measument is way down at over 100db level. How would that be observed as? A signature sound?
Most likely, that distortion is in the audio section (the reviewer hasnt stated), as the 1z uses upgrade caps over the 1a, and has a noticably better sound.
Also, this is not clipping distortion, and I found it unusual that you can tell the firmware is purposely limiting the output, because there is no audible sound of strain at maximum volume.
Very clean maximum volume.
As stated earlier, on the balanced output, it actually has enough power, so not sure why most would propagate the "saying" that it had a lack of power.
This is were more testing would show the Sony has an interesting performance behavior for such (low) output numbers.
Here is a link to a video where the Sony (1z) is cleanly playing a HD650 at maximum volume and it doesn't sound like it lacks power.
https://drive.google.com/file/d/1wcvAWmaUszO7NO52hSnMHW93KseLc0h7/view?usp=drivesdk
Yet, I would not use a planar or HD800 on it of course, but the Sony is surprisingly not bad at all, and if using IEMs its a moot issue.
The real issue would be how it sounds in comparison to the competition.
The competition also has great sounds.
I would say most all the latest daps in general are getting very close (if not already) to desktop level performance.
I see Daps taking over the desktop market, IF they implemented a line out feature.
This will liberate many audiofiles from their desks or livingrooms to move about the house, while smartphones might take over the "outside" portable market.