... I find myself cracking my brain trying to discover what on earth Luccini and Quattro have in common...

I'm failing miserably.

And yet this work still makes me grin for some reason.

Could be that Quattro's name is Italian for 4, but that's kind of a stretch as far as "things in common" is concerned.

*Glances at tags*

...then again it could be a seiyuu joke...

I think its a seiyuu joke, as Chiwa Saito voiced both characters. That's the only thing that makes sense here.

http://en.wikipedia.org/wiki/Chiwa_Saito