Topic: digi968pad installation and piggy-back cards

I have had two of the above cards sitting and never used for the last six years, since I was using a Wersi EX-1 expander for my music needs.
Its my intention to use the above two cards in possibly a piggy-back position, and am asking what are the potential advantages of doing this.
I have no interest in recording etc, and my only needs are audio playback of various VSTi programmes mainly piano using Vstack as host.
Since I know nothing about setting up these cards, any advice would be appreciated.
I am using a Dell P4(3ghz), with 865PE board and 4 gig memory.