Many here despise remastered albums because of the whole "loudness wars" issue, and often times it is true that remastered versions of cd's do sound worse (too overdone, hamfisted, lack of air, even distortion).
But some, imo, actually enhance the original cd pressings. It is up to you to compare the two and see which you prefer of course.
SHM, however, is a total gimmick. The material the cd is made out has nothing to do with how it sounds, just like with gold cds (of which I own a few dozen). What DOES is if the company producing the SHM remasters the source tape and thus plays with it's levels for the negative (to make it louder in order to attract the non hi-fi crowd that equate LOUD with good sound). But if a laser could read the 0's and 1's on a piece of wood there would be no sound difference between it and a plastic, gold cd, or SHM cd. 0's and 1's are 0's and 1's.
I'm not sure about K2HD's, but I'm wary of all these "hi-res" formats since, afaik, the human ear can not detect the differences they are supposed to make (i.e. they expand the frequency range way beyond what the human ear can hear). But I'm not totally sure on this issue as I haven't researched it enough, but I've seen strong evidence against it (and it sounds like typical audiophile pseudoscience and marketing hogwash), for instance some links itt:
http://acapella.harmony-central.com/showthread.php?1971483-The-myth-of-high-resolution-audio-busted! (the first link is broken and is found here:
http://theaudiocritic.com/plog/index.php?op=ViewArticle&articleId=4&blogId=1).
I also have a DAC that can play these formats and a cdp that will play DVD-A/SACD as well. No difference between the regular cd and DVD-A/SACD or the rips I took from them imo. Basically only perhaps recording in high bits makes a difference, but not mere playback delivery. Save your money.
Finally, if your cd is very worn but still plays fine, then you could try to rip it to a lossless format for preservation of the music as it were. No need to "upgrade" to a newer version, especially one that might be overly mastered (SHM) and thus will actually sound worse than the original version. When I buy cd's (that I rip to FLAC) I always try to get the original non remastered version. Then, if I really like a particular album, I'll get a remastered version of it on cd to rip to FLAC to see if it is an improvement or not. Sometimes it is, but most of time it is not. But any SHM's I've heard sound terrible because they are so overly mastered (again, to trick the consumer into thinking the plastic used somehow makes a difference when all that is being done is a totally hot remaster).
All the above is jmv (just my view) and I will not argue it, but I could, of course, be wrong (though not if I am understanding the science behind such things). You are free to try what you wish and let your own ears be the final judge.
Also, welcome to AK! :thmbsp: