there would be a big difference. i guess how notable this is depends on what speakers you have. ive got 6" 'something' speakers upfront and 6x9 infinitys in rear with 12" pheonix gold sub. fronts and 6x9's running off my pioneer 6850 deck which you can adjust almost everything i guess! just do this instead (it'll be easier) on your headunit, not sure if it was fade or balance, but turn the thing all the way to FRONT ONLY. is there a sound difference? now turn it back to zero or watever it was on before. you should notice a difference, but HOW different all depends on the quality of speakers.