Just as a counterpoint, here's a complete and thorough debunking of oversampling & bit-depth:
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The gist of it is that as a practical matter there's no point in anything higher than CD quality 44.1KHz 16-bit. The Nyquist Theorem is still correct when it comes to digitizing audio. In fact higher sampling rates may introduce problems.
Lossy compression is a different issue though.
I kind of skimmed through but seems like they didn't address the quality of the actual playback hardware device. The author seems to assume perfect playback by the hardware. I find music played from my iPhone through a quality system to not sound very good. Bad analog signal handling? The Pono seems (in my admittedly brief experience so far) to blow my iPhone away in that respect.
Possibly final comment: Pono Player 2 will probably have wifi and a remote control. Bah.
The Nyquist Theorem is correct, but misapplied to digital music. In fact, Nyquist is frequently misapplied to many engineering disciplines. But we won't go too deep into that. I'm not questioning Nyquist, just the application. Just remember that analog or acoustic audio energy as it is ingested for sampling doesn't ride on a carrier signal and therefore has no fixed time domain which Nyquist requires.
What I can say subjectively about Pono is that I've done much head-to-head comparison in what I consider my most applicable use case for the device - portable music and in particular car audio.
My car is new enough that all it has is USB/Bluetooth/Aux for audio. (In fact it's a 2015 and the sound system is of the premium variety - which is taken with a grain of salt as we're talking about consumer level products) Anyway, what it comes down to is that my choices for music are effectively compressed a'la iPod/iPhone grade device, or uncompressed via Pono. Most of the music I have downloaded to Pono is 96K.
As I started with Pono, I was happy and sure I liked it, but the nuisance of manual control and cables stuffed into the console made me reconsider. So I switched over to an iPod which gave me the convenience of heads-up display and integrated controls. But I had the feeling I might be missing out on sound quality. So I A/B'ed extensively with the same sections of the same tracks looking for something that was above and beyond confirmation bias. Here is my conclusion:
The most obvious difference with the higher resolution tracks is the definition of very specific types of sounds. For example, when a drummer is riding the bell of a cymbal it sounds real, immediate, and present. It's like you have an unobstructed path to the source. With the compressed audio, you lose the very palatable sense of the material - the metallic sound - the crisp attack. This phenomenon appears with almost every intersection of sound and material. The distinct metallic, woody, nylon, plastic, you name it quality of any material was far more evident in the high res-track.
The second thing I noticed was that the separation on a per-instrument basis was much clearer. There are about 5-7 new elements I've discovered across a library of songs that I've known by heart for over two decades, inclusive of owning the CD's since day one, and inclusive of owning the remasters which are the source of both the CD audio and High Res audio.
As a secondary benefit, I am now able to play along with similarly high-res songs via Pono Music World as opposed to iTunes (which has most of my music in 44.1 by default), and while it isn't nearly as pronounced a difference, what I can say is that I also can hear individual instruments within the tracks with greater clarity and separation. My playback environment consists of components that are a notch up from consumer level and aside from the room itself are on par with most professional studio gear.
Having an external control for the Pono would be a nice add for the car use case, but as long as you like your playlists and don't feel the need to skip ahead, then you'll be ok.
