So Sound Quality aside, its an ZX507 with bigger battery/screen.
it's very interesting.
I presume WM sound engineer Mr Sato is what is known as a 'golden ears'.
I work in radio and music. I'm very, very protective of my hearing. But all hearing deteriorates over time.
Inescapable but unfortunate biological fact.
In the new video Mr Sato talks about doing a/b listening comparisons - re the new capacitors, solder etc - to make 'incremental' improvements to the WM1Z.
The S-Master stays the same.
There's a definite Japanese / Swiss ' handmade' (Patek, Grand Seiko) thing going on here.
Because what you always see on forums is that Sony's players do not play well in terms of benchmark testing (vis A&K and DAPs using THX tech with black silent backgrounds). They do not score as well....
But there's a musical euphony that some of Sony's DAPs have which is not really graphable - which is what draws certain ears (mine) towards their playing of digital files.
And I'm not talking about the vinyl revival 'back to warm' which to be honest in physics terms is just adding a reassuring pink noise filter - the physical interaction of needle on plastic - to everything - making it sound 'warm'. That's all vinyl is (for heaven's sake you have to take out the base to physically make the record and add it back in like a thickener using the RIAA curve with a preamp).
Indeed
@MrWalkman allowed me to hear (and we know with region sound changes) that software can actually 'warm up too much' a good thing in the case of the hardware of the WM1Z.
This Sony musicality is really this a/b testing by one person, maybe a few more.
The irony of course is that the people that can afford to buy a 400,000 yen DAP will already have hearing that will not be able to hear of 16k, most likely it will be 14k and falling....
Including the designer....even if he is an outlier in the aging process....
With NAP's modding of WM1s we know better components can be put in - but the ear's ability is the baseline that as Hendrix said - are 'castles made of sand...that slip into the sea...eventually....."