I JUST got the discrete DAC in my NEX3S to work, it only works with a handful of apps of which only the default music app(which I previously didn't bother to even touch) actually gives the proper quality boost, but it's well worth it and now I no longer use Neutron most of the time(so unfortunately Neutron doesn't work with the proper data pipeline, it was using the SoC's processing the whole time, still impressive for what it had to work with I suppose).
The DAC with the default player uses less power than Neutron(despite a warning about "hifi mode" power consumption), yet has monstrous driving power for a phone, it basically properly drives a pair of strange niche single BA IEMs that have ~85Ω impedance and ~95db sensitivity. The DAC is good enough that even though the EQ in Vivo's player can't touch Neutron's I hardly feel like using it for most earphones. The DAC is strangely forgiving to output devices yet very revealing to source tracks, which led me to finally determine that one of my FLAC files was faked(it always sounded off, but I couldn't really tell from the spectrogram). I have the L3P (IIRC~$400 when bought) to compare with, alongside Sony's SX2000(flagship non-DCM recorder, because the DCMs are too cumbersome), an old Dragonfly Black and my laptop with the B&O stamp of approval(high driving power but otherwise unremarkable 3.5mm output), my NEX3S running the discrete DAC blows all of them out of the water. L3P comes closest in LO(used as PO with the amp bypassed, I believe, because there's still volume control in LO for this model yet the driving power is weak enough that only certain BA models are driven properly), but the difference in definition is still stark, and the phone works with so many more devices compared with L3P in LO.
So if the L3P was worth ~$400, basically all in sound since the system is entirely barebones...I think the NEX3S is worth $800, in sound alone, though I got the whole package for cheaper than that. Now as for Sony...I had a listen with the 1st gen black brick years ago...thoroughly not impressed, which is what actually got me to buy the L3 in the first place, then L3P came out shortly afterwards with an upgrade campaign, I took the leap, turned out very happy with it(the LO happened to play nice with my CIEMs), and it served me well for years until recently its battery is failing and there are now weird quirks with the system, barebones as it is it still has quite a few bugs...unless Sony does something radical with the hardware and the tuning I don't think I'm gonna be impressed with this ZX707, which IIRC is a bit cheaper than the 1st gen black brick.