Hey Ecoustics experts, long time reader, first time poster. I had a question about the actual differences between these two units, which both seem to be highly recommended on near all comparisons vs Alpine, etc for their price range. Comparing the two, I saw that the 770 has 4v preout vs 2.2v on the 670. If I intend to install an amplifier anyways, will that make a difference? At the moment, all I have in my car (1991 Honda Civic Hatch) is a set of Infinity's in the door (not positive on the model, can double check). The price difference between the two, so far as I can tell, is about $70. Is the 770 worth that extra $70? Thanks a ton in advance.