Reply to Home Studio - Sound Quality

So i'm starting on a home studio set up...

2 x KRK RP8 G2
1 x Focusrite Saffire 6 USB
2 x SINN7 MoPads

May add a KRK 10S sub at a later date but i believe the RP8's will handle things well enough.

As I'm looking for the best sound quality I can possibly get from the speakers coming from my macbook would you agree with the choice of soundcard (bearing in mind i am on a budget similar to what i have proposed)? Also am I correct in believeing jack (Soundcard) -> jack/XLR (Speakers) would give the best quality and if so can anyone recommend the best cable and manufacturer for the job? (Been looking at Die Hard not sure if they make decent cables?)

Thanks,
Barghy