I need to decide which is best for my situation. I have a 91' Accord 4dr SE with polk 6x9 EX693a's in the back and eclipse 6.5 8263's screwed in the door well hole where i removed the plastic OEM 4" speaker holders. I have no Amp or Sub(I listen mostly to classic rock) and would like opinions on which of these two HU (5500 or 550) to get and what the diffs are. Any other recommendations on this basic setup would be great, like will these speakers and the HU go together well?