Thrillin' Dylan   Every so often, greedy (or is it desperate?)
record companies dip into their overmined vaults and rejigger
classic albums, fiddling with the sound a bit and slapping on a
''remastered'' sticker in a cynical bid to ensnare music
fanatics. This is not one of those times.  Columbia has finally
gotten around to revamping the Bob Dylan catalog, and the
results are pretty spectacular. On Sept. 16, the first batch of
CDs hit stores: 15 beautifully packaged discs spanning his
entire career, including a handful of certified masterpieces:
''The Freewheelin' Bob Dylan,'' ''Bringing It All Back Home,''
''Highway 61 Revisited,'' ''Blonde on Blonde,'' ''Blood on the
Tracks.'' (A second group, ''The Times They Are A-Changin''' and
''New Morning'' among them, is due next year.)  Although high-
end-audio buffs will get their geek on playing back the titles
in the hybrid super-audio (SACD) format (six of the discs are
also available in a 5.1 surround mix), what really matters is
how they sound on a conventiona