I recently purchased my first HT and want to upgrade my front speakers.I am curently using a yamaha rxv 540 receiver with KEF Cresta 30,20 and 10's speakers and a Celestion sub.I am thinking of changing my front speakers to Paradigm Monitor 7's and use my Cresta 30's as rear surrounds.Do i need to change the centre speaker also?Will the Paradigms offer better sound than the KEF's?Hope one of the buffs will be able to help me.