Ways to guess the recording technique of an 80s/90s album without a SPARS code?
 

Obviously virtually all music recorded now is fully digital, and virtually all music recorded before 1980 will have originally been analogue, but for those albums released in the late 80s/early 90s when both techniques were in use, is there any difference between sound quality which would give a hint into how the album was recorded if there's no SPARS code (AAD/ADD/DAD/DDD in the case of CDs) or not? I'm pretty sure I remember someone saying elsewhere on the internet that they were able to tell whether something was digitally recorded or not by listening to it, and it would be interesting to know what the difference is between a digitally mastered analogue and digital recording.

An alternate way to finding out the first letter would be to look up the recording studio and find out what equipment was in use there at the time.