So, basically, SHM CD is another attempt to entice people to pay more money for, essentially, the same product.
See Also....
Gold CDs
SACD
DualDisc
DVD-A
Isn't DVD-Audio actually a superior format, with a mix? I got my Pet Sounds DVD-Audio autographed by Brian at a GIOMH signing years back. Since then, I've always wondered how many autographed copies of Pet Sounds on the little-known DVD-Audio format exist on this planet.
DVD-A & SACD are high-res formats - 24bit/88.2khz sample (SACD) or 96khz sample (DVD-A).
There are a couple of mixes on the PS DVD-A - Brian's original mono mix is presented in high res, remastered from the '66 analogue safety copy.
The DVD-A is set to be superseded by the hotly anticipated Blu-Ray Audio should it emerge - perhaps the Blu Ray-A will contain the original mono mix at high res remastered from the flat digital transfer to 1630 tape Mark L made back in the day, as used on the 40th anniversary CD/DVD set.