What you need to know up front is that K2 HD is not a new format such as SACD or DVD-A. It is a normal Redbook CD that will play on anything that plays CDs. No special player or decoder is necessary.
What K2 HD is, is a new mastering technique that it said to bring the sound 100KHz and 24-bit resolution to the standard CD which is limited to 44.1KHz and 16 bit. It is from the labs of JVC which brought us JVC XRCD for one.
Notice that the first quality listed is "Ambience of Analog Sound". Ambience, what some call reverberation, is very difficult to reproduce. It is one of the first thing to which I listen when evaluating a component because it is so telling and easy to decern if you know what to listen for. I've been involved in studio recording for over 30 years and have a hard-disk based studio in my home now, so I have been working with, recording, mixing and mastering digital reverb for many of those years. We first had 8-bit digital that was very thin and grainy and when it tailed out, it sounded like a sparkler fizzling out. 16 bit came along and things improved with a richer, more dense presence, but listening to the end of the reverb still revealed a raggedness that natural reverb does not have. Now there are hundreds of different reverb generators available to the recordist, ranging from free VST plugins to hardware based boxes costing thousands. I own maybe a hundred different reverb software packages and three hardware boxes from Lexicon, TC Works, Alesis and so forth. They all sound different.
I said all of that to make a point. It is immediately apparent when listening to the new K2 HD disk that there is somehow at least the illusion of a higher bit rate. I don't hear the telltale raggedness from cd ambience. Large room sound is dense, full and very long with a more natural tail off.
Do you have a digital camera? Imagine audio bit rate to be like a camera's pixel count. The more pixels, the better the picture, right? It's the same with audio. The higher the bit rate, the higher the resolution. Of course, there are other factors, but you get the idea.
If one really wants to be analytical, all FOUR of the qualities listed above in the green graphic have to do with what I was just describing. More ambience = higher resolution = lower distortion = richer soundfield.
A lower noise floor and less distortion also equates to more of the quality some call "air". It's the space around instruments and voices that is either clean or dirty, spacious or congested. The examples of the K2 HD are clean and spacious.
It is interesting that JVC compares their new digital process to "Analogue Sound". It is precisely these qualities that good LP playback delivers rather easily and with which digital has always struggled.
Does K2 HD blow away SACD or DVD-A? No. Is it comparable? Yes. K2 doesn't do multi-channel - yet, but overall sound quality seems to be in the ball park without all the attendant downsides of both SACD and DVD-A.
The problem is, since it is a process that takes place in the mixing studio, it does nothing to improve the sound of your existing CD collection. Like XRCD, it will most likely never make it to LA, NY or the average new CD release. It will probably be relegated to the audiophile community - a niche product used mostly in reissuing yet another round of Miles Davis releases. And that's regrettable.