Have you ever heard a system with nice comps up front and no rear fill except for a substage? I didn't think I would like it at first without real fill, however, I spent a little more on my front components and skipped the rear fill for a try and I have never looked back. With nice comps on an amp you wont hear your rear speakers anyway, and if you do it will only pull the stage backwards and unless your rear speakers are as good as your comps you will sacrifice the sound quality of your good comps with mediocre or less then steller rear speakers. Spend extra dough on front comps, and then add rear speakers if you must have them or stick to your stock speakers back there and fade to the front. no need spending money on something you'll barely hear anyway. food for thought.