Caps on a Powered Sub


I have a integrated amp (Music Hall a15.2) with an inexpensive powered sub on a second system. I want to use the Hi pass speaker wire connections. The sub's crossover obviously isn't the tops in quality. Is there any way I could get some good quality caps and use them on my bookshelf speakers or on the powered sub to get some better sound? I would like to not use the bookshelf spk full range. Thanks.
drjjpdc
I did not get any caps yet. I was asking where do I put them? The bookshelves, the powered sub, etc.
Orpheus,

Thanks for trying to help but I have to tell you I am very technically challenged on parts and where they go. Are you saying add them to the existing crossover in the powered sub (below) and then attach a cap to the speaker wire on the bookshelves? Once I decide what to do, I do have someone that can help with my technical shortcomings.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-784