Puzzle ZTOX 

Workings

Hint
Look at the piece by Bach, and the single.

Answer
Composer   Format  Length
Beethoven  album   6
Holst      single  7
Bach       CD      8
Butler     DAT     9

Reasoning
By (1), the piece by Bach lasts 8 minutes. By (3), the single lasts 7 minutes.
Composer   Format  Length
                   6
           single  7
Bach               8
                   9

By (4), the piece by Butler is on the DAT tape. But, by (2), this can't be the shortest, so it must be 9 minutes long.
Composer   Format  Length
                   6
           single  7
Bach               8
Butler     DAT     9

By (1), the CD can't be the shortest, so must be 8 minutes long.
Composer   Format  Length
                   6
           single  7
Bach       CD      8
Butler     DAT     9

The album must therefore be 6 minutes long, and by (3) doesn't contain any Holst.
Composer   Format  Length
           album   6
Holst      single  7
Bach       CD      8
Butler     DAT     9

Which means that the album was the piece by Beethoven.
Composer   Format  Length
Beethoven  album   6
Holst      single  7
Bach       CD      8
Butler     DAT     9