As Kr4 said, a cap will do the trick BUT you will need to know the impedence of your bookshelf speakers at 80hz and whether you want a shallow rolloff(6db per octave) or a sharper rolloff(12 or 18db per octave).
Also, the quality of the main cap will make a BIG difference in mid and upper octave transparancy but a plain non polorized electrolytic will also do the job.
It would help if we knew the brand/model of your bookshelf speakers...
Cheers
Also, the quality of the main cap will make a BIG difference in mid and upper octave transparancy but a plain non polorized electrolytic will also do the job.
It would help if we knew the brand/model of your bookshelf speakers...
Cheers