newbie DAC question

Hello!

I broke into the HiFi world about two years ago and l would love to know if a DAC would improve my system in a way that's worth my while. I currently have the following setup:

- Elac Debut B6s
- Music Hall A15.2 integrated
- Onkyo C7030 CD player
- Sextet and Bel interconnnects borrowed from a buddy
- Speakers are on stands carefully placed where they work best with the carpeted room.

I've read good reviews on the Musical Fidelity V90DAC and several Schiit models, but I can't determine, based on any literature out there, if my setup is at a level that would make a DAC worthwhile (or even noticeable). If it WOULD make a difference, does anyone have any suggestions for coaxial or optical interconnnects to go along with it?

Thank you much!