Chinese DVDs now have BluRay symbols on them as well. Very confusing if it's a genuine BluRay. Most of the time they are simply a DVD.
The Blu-Spec is similar to SHM: a specialized surface said to reduce jitter & increase readability.
Never heard a Blu-spec. The SHM's I've heard have varied from very good - to awesome; my question continues to be is it the mastering, the surface or both.
I have 2 (intentionally) identical copies of an official sacd here (provided by our own Jim); 1 SHM, 1 not. I haven't yet been able to decide if i definitely hear a difference; though part of that is my exhaustion level. Will post here when I make up my mind, though long story short: a table in my office with about 20% of my inventory on top of it in racks collapsed yesterday, so it may be a few days before it's back to normal here. To quite Alice Cooper, Welcome To My Nightmare...........
From SHM cd's I've actually listened to (a GENERALISED statement is that Universal's tend to sound much better than their USA counterparts while Warner's tend to sound only a little better) is that's it's probably around 75% mastering & 25% the special surface, but that's only a guess.
The above is partially based on the fact that I have also heard rips where a burn of a Universal SHM can sound pretty amazing which would seem to lend credence to the theory that the Japanese tend to have better mastering skills &/or criteria.
In fact (this is from memory, i never did an a/b) I heard rips of the 1st & 3rd Steely Dan that were so good i bought the real shm of the first & while this is going to sound odd, my memory is that the rip sounded slightly better!
At one point Michael Fremer was advancing a theory that a well burned cdr had less jitter than a factory pressed, so it's possible I wasn't imagining things!