i'm thinking about getting a new head unit and front speakers

any recommendations?
i've put my eyes on an Aiwa CDC-X204 receiver and a pair of Infinity Reference 6002si 6.5" shallow-depth speakers

should i bother upgrading rear speakers, or switching my choices to the next models up? (Aiwa CDC-X304 reciever and Infinity Reference 6012si 6.5" shallow depth speakers)