Hi - I'm very new to this, but I did purchase a Fubar IV Plus so I could connect it to my Airport Express via optical - it makes my music sound wonderful.
Reading the posts here I'm sure other DACs would be great too but so far no complaints. I have had audiophile friends use it with high end headphones and the music sounds amazing.
No idea what jitter is - i.e. what it sounds like - so can't comment on whether the Fubar makes it better or worse.
Very happy with my first DAC