Speaker Question - Optical Out or 6-speaker out?

Hi everyone,
I just setup some new speakers (Logitech z-5500), and I was wondering if there is a noticeable difference between the 6-speaker output (3 analog cables) and the optical-out settings? Since the 3 analog cables came with the box, I have them connected to my X-Fi. The X-Fi supports optical out also, but I’ll have to run out and buy an optical cable.

Long story short, is the quality difference between the analog connection and the optical connection kinda noticeable?

Thanks!
Kirupa :beam: