Actually according to many interpretations of copyright laws you'd be
within the letter, let alone the spirit, of the law if you own ANY genuine
published copy. CD, LP, Cassette, 45 or even 8-track you have already
paid for the work, and thus have a right to make duplicates for your
own use under the "Fair use" doctrine.
HOW you make duplicates is up to you.
Though the record companies wouldn't agree I'd dearly LOVE to
be sued by one on this issue, they'd be "Bent over & spread wide"
for the court president I'd get them to finance the creation of...
Aside from all the dire warnings about the illegality of
"unauthorized duplication", the fact is unless you are making
copies to give away or sell, any duplication you do is "authorized"
under US law.
IF you live elsewhere your have different rules.