The fun part of vinyl, in addition to listening, is the research on pressings.
You'd be shocked at the qualitative difference between two otherwise
'identical' records, whether comparing contemporaneous old pressings
from different mastering engineers and pressing plants, or the 'right' old
pressing vs. later reissues and remasters. For the Blue Note stuff, I think
most people go for the Music Matters reissues and some of the catalog
was done by Analogue Productions (whose retail outlet online is Acoustic
Sounds).
How do you discern the differences between different pressings? One way
is to buy a lot of different copies and listen to them. Not cheap, even for
relatively inexpensive old vinyl. Another way is to read listener comparisons
on places like the Steve Hoffman forum, where matrix info is provided. In
some cases, there is a pressing that is profoundly better, in other cases, it's
a question of preference, but in many, many cases, the older records are
going to sound more alive than the remasters (not always true- some of 45
re-do's by Analogue Productions are extremely good). What I have found is
that a lot of the remasters of rock tend to sound more 'audiophile' in that
they have more detail, but aren't as rich, decay times and bass sound
different, sometimes the remasters are a little bright (I wonder if it is a more
'modern' sound, or simply the tapes plus modern gear in the mastering
process). If you are buying old records-and many can be found more
cheaply than the 'audiophile' re-do's, you'll need a good cleaning regimen.
I'm not sure Audiogon is necessarily the best place to read up on various
pressings since it is more gear-centric, though there are many
knowledgeable vinyl people here. If you simply type into a search engine
'best vinyl press' and name the record or artist, you'll find sites and blogs
and comparisons. Not saying you should take anybody else's word as
gospel, but in many cases, there are preferred pressings where you'll see
consensus. (I've been focusing on late 60's -early 70's psych/rock/folk so
that's where I've found a treasure trove of info re different pressings on the
Net; I suspect you can do the same with jazz records, although the above
mentioned re-do's are pretty good). Interested in what others have to add.
good luck!