Really starting to like the more refinements compared the previous installments. Especially the added detail percieved while the bass is kicking. It is definitely more higher quality sounding but higher quality sound doesn't always translate to more enjoyable sound depending on your personal tastes. Good example is Sennheiser HD800, one person's holy grail but could also be another person's "What?" Technically beautifully sounding but not maybe the most "musical" if that made any sense. Anyway I'm just trying in a polite way of saying I definitely hear this new ZO as a clear upgrade sound quality wise but that necessarily won't necessarily directly translate to getting more excitement/enjoyment feeling while listening. Having said that though, the more I listen to it the more I start enjoying it, it needs a bit settle-in time for your brain.
And I might go as far as saying I like it better overall than the ZO2.1 which was my personal fav before now. (I'd say it's a greater boost in SQ than the amount "fun-factor" the ZO2.1 competes with leading to the sound quality boost win a bit over the "fun-factor" in ZO2.1)
Unfortunately I had hoped for a lower noise floor compared to the previous ZO but it doesn't seem that much different in that aspect. Listening out of noisy sources like onboard sound sorce that is very noise environment, the point where the electrical noise is percieved in the chain starts at roughly equal levels as before. So I'm not THAT surprised if some people may pick up additional noises from the chain especially with smartphones and what not out of the headphone jack with less than ideal noise level issues due to bad engineering choices. With good sources ZO will go to dangerously high volume levels and insane (I'm talking STX II here) before noise floor is getting an issue but I had hoped it was sliiiiightly bit better with noisy sources too.
The SVT-less config in the ZO FS+ is also brilliant on its own, unfortunately I personally have become spoilt with the coloration SVT brings to the table that personally captures me since it gets me engaging with the music a lot better. In comparison turning of SVT the music becomes so "sterile" and polite somewhat like it suddenly lacks a bit meat (this also include at settings 0-0 so it's not just the bass) but I admire how it sounds in comparison to other portable amps I've tried, really good detail and very neutral "flat". Not warm, not bright, flat. They didn't kid when they said that the secondary amp config would bring a "flat" sound. Some audiophiles I may expect they'd prefer SVT-less config because they are more acoustomed to such sound and possibly it could be ever so tiny bit easier to make out microdetails with that. I'd put it like SVT is meant to enjoy music while the SVT-off config is meant for analyzing the sound so there the preferences will play a strong role in how you want to enjoy your music. Since FS+ packs both, I'm glad I can take advantage of both aspects depending on my needs (for mastering music I like to check with both configs to get a better idea)
My preferred setting as of right now is B: 32 - T: 3. I'm surprised by the guys who turn treble up to max, you guys don't seem to enjoy a more neutral timbre do you?
Don't take that offensively though as it's just a matter of tastes but the ZO will definitely exaggerate the "sparkly stuff" at such setting more than another amp without the treble adjustment. Possibly it's a case of volume-mismatching, as I turn up the treble, I also have to start adjusting the volume a bit or vice versa. What I'm trying to say here, if I don't then turn up the volume a bit when lowering the treble a bit (I don't know exactly how it goes but say 1 vol step per 3-5 treble steps or whatever), of course you will be "tricked" to think the higher treble setting sounds better because we interpret louder as better.